Sick for a month

About a month ago I started vomiting everything I ate. And when I didn't eat I vomited stomach acid. Well this lasted for about 4 days then I went to the doctors for the first time. He ran blood test on me and couldn't find anything wrong. He said it is probably a virus or from stress. He put me on comp for a few days and that helped. But then I started getting diarrhea. I figured that was a reaction to the comp or something. Well I ate very little for that week. When I started to feel well enough to eat I could only eat about a half a sandwich and I felt sick (like i was already full). Well I havn't been able to eat as much for the past 3 weeks. I still feel sick sometimes after I eat. I feel nauseous when i first get up in the morning (i also have acid reflux so that might have something to do with this). Well for the past couple of days my middle left side (like middle abdomen) has been hurting at random times and whenever I use the bathroom. Does anybody know what could be causing this? Or does anyone have any advice for me besides going to the doctor? Thanks so much . . . Amanda