What is wrong with my body?

I have been told that I have swollen fibrous glands in my breasts, and went to the doctor.  He gave me Hydrocodone, Ibprophine, and a muscle relaxer to help with the pain which actually doesn't work at all(I had an attack while writing this and was inches from screaming and wrything on the pain on the floor).   I am also on birth control.  My period started late Tuesday or early Wed. morning.  It lasted until Thur. afternoon to mid evening.  There is still a little bit of blood but not much at all.  I have had sex, but am on the pill (28 days) and have used the withdraw method along with it.  Could the stress from all that pain have cut my period short, or could I possibly be pregnant?