Flo'da--
Timing yourself is tough, as you know. Anytime you try to time yourself in a sprint, you will slow yourself down as you will be thinking about the timing to some extent.
I have found that self-timing is almost useless in the 100, for instance, and basically just as bad in the 200.
So then the question is, how to judge your speed, to see where you are at and where you are going? It's really hard--you will either need some sort of photocell or magnetic timing device, a friend/training partner who is very reliable in their timing ability, enter a bunch of FAT meets, or judge yourself over time against training partners whose speed is more or less known at any time of the season.
Hard, I know. The important and easiest thing is training partners. Fast tempo and drills you can do on your own, but to judge your speed you need others around.
Tying up in a 100--been there, done that! It is totally possible, guys have even done it in Olympic finals. Stride gets short and choppy, moving seems hard, cramping can set in, running feels like fighting.
First, if you did two all-out 200's and then an all-out 100, all in one session, then FOR SURE you will be tying-up in the 100! That's not YOU, that's EVERYBODY.
Heck, you should have been tying-up in the second 200, and no doubt you were.
When doing these "all-out" types of time trials, really go easy on the start. You can go 95-98% of "all-out" just by easing off the start. It might really affect your time in the 100, but it won't be so bad in the 200. Remember to relax, even on the acceleration, and make sure you are breathing the whole time, and that you're not making fists. If you do this, you will be able to do 2x200 really hard during the same session, and maybe even have enough left over for a hard 100 with a "soft start".
When you're doing a 200 or a 100, and if you're not used to competing at that distance, I think that your mind can stop you before you reach your maximum potential velocity--that is, you drive out with a certain stride frequency, and you "cruise" for a short period at the max velocity you can achieve with a particular frequency and stride length, before you have to actively "think", then suddenly transition to either a longer stride, different stride frequency, or both, and the form that enables this new combination.
Don't be satisfied! IF you ever "catch yourself" in this pattern, do something to break it. The transition and/or mid/late acceleration is a much-neglected part of the race, but is maybe the most critical. It is easy to get stuck below actual max, because you are already going fast, and it feels like you have already expended lots of energy because you have started and accelerated from zero.
Some guys get up into their final running posture earlier, so that their "sudden transition" happens sooner, so that they lose as little time as possible at below-max speed. Some try to break the cycle through training things like accelerating downhill, which depending on the slope will force you to reach your max velocity and beyond. Don't go too steep, otherwise you will have to slow yourself down and/or kill yourself, and it will be counter-productive. Learn the feeling of getting ALL THE WAY to max velocity smoothly, without any break along the way.
That is kind of an advanced thing, though, for people with good top-end but a sticking point along the way.
If you don't think your max speed is all that and still need to improve it before you have a problem like the above one, think particularly about stride length, and how to achieve it, during the majority of the 100m distance. At the start and early acceleration, you can practice using short, quick steps to get yourself moving while coming out fairly upright, which is something you will be doing if you haven't got sprinter power yet in the legs. tat-tat-tat-tat-tat-tat-tat coming out of the blocks, or out of your 3-point stance. Quick. Gets you moving, short quick steps. Keep the arm action restricted, too, you don't want to slow down your legs, or burn too much energy.
But after that, after you have gotten out, you can get up into your running position fairly quickly, and accelerate while in that position, rather than accelerating in a "drive phase" position like trained sprinters. Concentrate on stride length early, earlier than you might think worthwhile. To get a good stride length, try, of all things, running lower, closer to the ground, and making sure you get good knee lift. Too many people try to run too high IMHO, and spend a lot of energy flailing their limbs in the air, where they're not productive.
Stay low, and L-O-N-G. In this phase, concentrate on arm action, bringing your hand up pretty high and driving the knees forward. Run feeling like you are "curled forward", rather than sticking your chest out forwards, and your butt out backwards. Concentrate on holding your form through the finish, not just TO the finish, especially in the 200. Don't worry so much about turnover, leave that for the early acceleration.
Especially if you have felt like you are accelerating all the way out to 80m, this suggests a lack of focus as to where you are in the race, and the level of effort you're applying.
Alternatively, if you want to see how this works out in comparison to the above, stay in a "drive phase" until something like 60m, no kidding. Keep your head/eyes down, looking at the track, slightly more forwards as you speed up, but don't look forward until, say, 60m--then at that point, breathe and relax, and let the momentum you have developed carry you through the line. Or, if you feel like you have extra to give, then really try to hit that top speed between 60-100m.
Hard to tell what will work, as I have no idea who you are, but try those 2 opposite things and see what happens relatively to your time--coming up and looking forward and striding longer sooner than you think is right and from a position you think is maybe lower than optimal, or staying down in drive phase and looking at the track way longer than you think is right, then breathing and relaxing through the line, and only going hard if you still feel like you have a lot to give.