I had the same experience with pain after eating. I saw a GI specialist and had a number of tests done (upper GI exam, colonoscopy etc.). I found out after 2 years of being ill that I had Crohn's disease. I've reacted well to treatment and am doing great.
I'm not trying to scare you but you should get tests done to rule out any illness. Most of them are treatable if caught early enough. I let mine go too far to the point where I had to drop out of college and stop working. I lost soooo much weight that people thought I had an eating disorder.
Please go see the doctor and demand to have some tests done. Simple bloodwork is not enough, I started like you and I would hate to hear of someone else going through what i did...
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