I have had frequent constapation that goes away and comes back my stomach gets upset with mild pain. i have been checked for cancer and it's negitive.

Constipation: There are many over the counter laxatives that are gentle enough to take regularly. Also have you been checked for ibs or celiac? The pain you experience could be your intestinal movement/functional abdominal pain or inflammatory response or reaction to what you have eaten. Recommend increasing fiber intake and hydration. See md if problem continues.

May need blood tests: If you have had this your entire life it may be ibs…, not sure how you were checked for cancer (colonoscopy, egd?) i would consider getting your thyroid checked along with checking for celiac disease (gluten issue) and look for h. Pylori test. Also, take a look at your diet, see if anything correlates with your symptoms.

CANCER?: You should have a complete work up . Cancer is not really high on the list for your age. If all is negative you possibly have ibs with constipation.