Hi i am 22. I eat healthy and exercise weekly.  sometimes i have this pain in my chest in between my breasts when i breathe in deeply but it usually goes away.  Today i woke up at 11 am and it was back, but now it is 8pm and it hasnt stopped all day.  the pains are sharp and i have tried stretching and drinking sprite and burping but the pain wont cease. it feels worse than when i woke up, what could it be?
Avoid exercise which use your chest muscles. You can take some muscle relaxants for few days. Its only muscular pain, don't worry it will go.