Unexplained nausea for prolonged amount of time.

I am an 18 year old female, and I have been having unexplained and severe nausea for almost two months. I have been to two doctors, the first didn't know what was wrong, but took my blood and said that everything is normal. I saw my family doctor while I was home for the holidays, and he told me that it was a Colon Spasm, and gave me Dicyclomine to stop this problem.

The medicine he gave me helped for about five days, but now I am back to how I was feeling before I started the medication. I am weak, very nauseated, and I have no appetite. I do not vomit unless I am extremely tired, and I while my stool has been abnormal since I've been sick, there is no blood, it's not strangely colors and it has not been loose. There is no chance I am pregnant.