點解我有時跑步心口會痛???

How often you go running?? May be cause by lack of exercise, insufficient cardio-respiratory function(insufficient oxygen in blood), heart disease, etc.
Advice start to run slower, remember water intake/replenishment which is related.
Otherwise, if you do exercise regularly, better go to check with doctors.

去check下la... 可能會有事... 小心~