A few years ago when I was about 12, I was running a 5km race and randomly threw up with 100m to go. This problem continued, and in about half of the 5km races I did, I would throw up (usually with 100m to go). I stopped running for a while till I was 14 and was entering my first year of high school cross-country. I never once felt sick and actually went on to make the OFSAA (provincial championships for Ontario, Canada). Directly following this I did my first indoor track 1500m, and 600m in I threw up all over the track. I decided to take time off, and my coach recommended I take an iron supplement for the next year. I rested from December until March the following year, and got right back into training. Unfortunately I felt sick again and started to even get a sick sensation (that I could throw up if I pushed harder) in workouts. I continued until it got so bad and I had to break from June until the middle of August. I came back again and tried cross country for grade 10, but felt sick during every workout I did, so i stopped and took another break! I came back in late December of that same year and things were great. I did not race but workouts were going great without the sickness that I had been experiencing. I continued untill March. The following may be completely ironic, but my ear started to plug up when I started to exercise. Although this issue was very annoying, running was great and I had no feelings of sickness. After doing extensive research online I figured out that the ear that was plugging up during exercise could simply be fixed by putting my head down, to get blood flow to the head. For some odd reason this worked and completely eliminated the problem. The only issue now is that directly when this issue was solved, the sickness came back and just last week I threw up during my workout. I have tried many things at this point such as TUMS, and dairy free. Nothing has worked. I was just wondering if anyone has maybe experienced this, or even knows a possible solution.