>> bb/108385@105474
It can be nerves, spine, lungs, stomach, pancreas, and just anxiety.
You should go to the clinic on those days after you're done, when something aches, and ask for an ECG, it's free. It is advisable to try to provoke an attack before the ECG (to run down the stairs or something like that), then the study will be most effective.
For money, you can make an ultrasound, and hang Holter on yourself.