Hello, Thanks for the query to H.C.M. Forum. Here I want to ask one question that , you mentioned that there is pain from one month on left side stomach ( abdomen in my opinion as you are asking for ) and now the pain is on right side of stomach . I think pain is on both side of abdomen left and right side. As you stated that there is sometimes diarrhea , sometimes constipation , so pain must be on both side of abdomen on lower part , so may be , 1 Amoebic colitis as sometimes diarrhea and constipation present in this condition. Diagnosis can be confirmed by physical examination by a physician . Get in stool for E . histolica . 2 If pain is on the left side in stomach as you mentioned then may be due to Peptic ulcer disease . Diagnosis can be confirmed by upper G I endoscopy . Till avoid greasy, spicy foods, junk foods, alcohol, caffeinated drinks . Don t eat or drink 2 hours before lie down. Try raising the head of bed 4 inches above with blocks. 3 Cancer of large intestine as pain is regular from one month. Diagnosis can be confirmed by colonoscopy . Least possible chance. So in my opinion physician consultation will help. Good luck. Dr. HET