I started getting these when I was about 6years old. Its like a stabbing, tight pain in the chest. I found that I needed to take small breathes as well otherwise it really hurt. If i ignored that it was hurting and breathed in heavily i would then feel a cracking pain which was WAY too painful to continue. So i just waited for it to pass.   I went to the doctor and they couldn't find anything wrong with me. Over the years it has come and gone but I have figured out, for me, why I was getting it. I found that when I drank coca cola often that the chest pains would start. I also ate a lot of chocolate back then so it's possibly the caffine (not sure, but definitely was the cola). So i just stayed away from coke now, I only have it like once a week, and I don't drink coffee. This is just a guess that it's caffine though, all i know is to stay away from coke!! I'm 23 now and haven't had a chest pain in over 5years.   Hope this helps.