I keep feeling a sharp pain in my left side of chest?

I've been taking microgestin fe 1/20 and yesterday, during the day, I felt a suttle pain in my left chest and it then went away. But in the middle of the night, the pain came back and it started to get worst through out the night. Now today, it's starting to get unbearable. The pain is on and off and it kind of travels down my arm. I don't think it's a lung problem because the pain doesn't come when I breathe I'm or out nor am I short of breath.

My mom called the doctor to set an appointment and one of the doctors just said it was probably due to stress but the thing is, I am not under stress whatsoever. She also said it could just be the side effects of the poll and since I stopped taking it, it should go away.

I'm very concern about my health. I don't thin it's serious because I'm only 18 but I just can't stand this sharp, stabbing pain. What could it be?

I don't know if it's my breast or behind the breast, when I put pressure onto it, it tends to hurt a bit more. Whenever I sit down an relax, it gets suttle and sometimes go away, so I'm guessing it's a heart problem? Also laying on my left side keeps the pain from coming.

Please just help me figure out what it could possibly be.