<s>[INST] After I eat I get severe stomach pains, sometimes in the upper region only and it switches to the lower region or sometimes it's all over. I also have diarrhea and feel very clammy and nauseous and I sometimes experience back pain, this pain can last for hours, Do you know what can cause this? [/INST] HI. There are several causes for the symptoms you have mentioned..Let us start : the upper abdomen pain increasing with eating can be due to ulcers in the stomach and / or duodenum. Switching to lower / all regions can be suggestive an inflammatory pathology of intestine like enteritis/ IBS- irritable bowel syndrome / inflamed intra-abdominal lymph nodes. Backpain can be due to lymph node inflamation as already suggested , but would suggest me to rule out pancreatitis / gastric ulcers.So , to get a diagnosis you need to consult a Gastroenterologist and undergo upper GI endoscopy / CT scan of abdomen The proper diagnosis will lead to a very proper treatment in a guided manner... </s>