Should I go see my doctor or go to the hospital?

I'm a 21 year old female and am experiencing stabbing chest pains around my sternum. I'm wondering if I should go see my doctor or not. The pains started about 30 minutes ago and whenever they happen i get the wind knocked out of me. I'm not really sure what is wrong I suffer from heartburn and take daily medication for it but the pain feels like it's too high up in my chest for that to be the problem. I went for a long and strenuous bike ride today could I have pulled a muscle?