Thanks to everybody who replied to my post, I really appreciate the input. Lots of info about my side stitch problems, including an in-depth description of the stitches and a list of the prevention/alleviation tactics that I've tried, can be found at the following link:
http://www.runnersworld.com/community/forums/runner-communities/beginners/side-stitchesstomach-cramps
^I'm the OP in that thread, and I post under the name 'Striders.'
I'll respond individually to each comment below:
the average male runner- I definitely feel like an extended break from competitive running would be beneficial for me. While the side stitches are a big physical pain, they're a confidence-drainer too, and I need some time off to mentally recharge. As for seeing ''what the doctor says'', I've been visiting a reputable chiropractor over the past few weeks. My next appointment with him is on the 29'th or 30'th, and hopefully he'll have some helpful tips for me then.
what sport you play- I never said that the side stitches occur because I run too much (or, as you put it, need to run less). The cause(s) of the stitches are likely unrelated, or just minimally related, to my running volume. I just think that I should take a break from running because the stitches are such a pain (quite a fitting idiom, eh?).
help you- You really nailed it when you wrote "they totally ruin the sport of running." In my case, that's completely true. Thank you very much for the offer to help me find a good doctor, or to help me yourself. As I mentioned above, I'm currently seeing a chiropractor in the hope that he'll be able to solve this issue. The chiropractor that I'm seeing is the same chiropractor that several professional sports teams, such as the Toronto Raptors and Toronto Blue Jays, use (knowing that, you should be able to figure out my location =p Toronto).
FogRunner- I'm not sure I understood what you mean by "keeping my rib cage expanded." I've tried several breathing tactics, including breathing in a 2-2 rhythm, changing from inhale to exhale on the opposite foot from the pain, belly breathing, and exhaling fully. The problem with many of these tactics is that I can't use them during high-intensity workouts or races, as they restrict my oxygen intake too much. Do you recommend that I change from exhale to inhale while I'm in the air? Your statement 'if you must touch down at full exhale' seems to imply that, but I may be reading it incorrectly.
Less Than Snake- The pain I feel is a constant, sharp pain, which grows worse as I continue exercising (unless I slow down significantly). Lots of info about my stitches can be found at the link posted at the beginning of this message.
As for running on an empty stomach, that helped when the stitch problem first occured (way back in April/May) but now it doesn't seem to make a difference. Even at morning XC practices, when I haven't eaten in 10+ hours, I can still get stitches during runs.
I currently do ab workouts 3 times per week. As I wrote at the top of this post, the specific exercises I do are: standard crunches, bicycle crunches, V-crunches, toe touches, heel touches, flutter kicks, scissors, planks, and up-and-downs. I do 20-30 reps per exercise (except for planks [1] and scissors [10]), and I manipulate the exercise so that it begins to hurt around the 18-20 rep mark (for example, I'll do bicycle crunches slowly, so that my abs are hurting by the time I reach the 20'th repeat).
I'll incorporate sit-backs, pushups, and side planks into my routine, and I'll look up some of the other exercises you posted, such as V-sits. Once I figure out how to properly do them, I'll incorporate them into my routine as well.
I already do butt raises as part of an exercise routine my chiro has prescribed to me, although their main purpose is to help with a minor knee injury I got ~1 month ago.