Over past 6 months i have lost 20lbs.the weight loss was kind of sudden-lost 1-5lbs a week for a while. upper abdominal pain from feeling full from eating small amount of food.nauseated. friends think it's an eating disorder. how do i prove otherwise?

See your doctor.: Abdominal pain , unintentional weight loss, and early satiety are not normal, so if you truly feel that there is a change and that there is something wrong, you should see your doctor. He may or may not want to do tests at this point. Good luck.

Check up : Getting s good medical checkup would probably be a good start. Probably would want to make sure it is not your gall bladder among other possible considerations.