experiencing nausea off and on for about 4 years

I have been experiencing nausea off and on for about 4 years now. It has recently within the last 6 months gotten worse. I do have endometriosis, and stomach ulcers which I take prilosec for. It is getting so bad that phenergan nor zofran is helping the nausea. I don't know what else to do and really think my GP may be at a loss also, and I really don't want to go to another doc unless I absolutely have to because my GP doesn't make me feel like I am wasting her time. What would you suggest? I am willing to try anything!