Nausea after eating - not pregnant

For about two weeks now I've been really nauseated after I eat, whether it be a pack of fruit snacks or a bowl of soup. It's almost a gag-reflex feeling but I also feel like I could vomit, though nothing comes up. I've had blood work done for pregnancy and they ruled that out, but they didn't test for anything else which I'm worried maybe I'm sick with something else. I haven't had much of an appetite either, I eat about 2 or 3 small meals a day and last night all I could stomach was corn on the cob. I don't eat greasy foods, everything I eat comes from my kitchen (mostly salads or lean meats). Today I just ate half a bowl of top ramen chicken soup and shortly after I felt like it was going to come back up, but nothing. Any ideas?