I've have radom pains in stomach and back. lost 15 pds 2weeks vomittid once. lots of gas plus constapation. odd looking stools.head ached. pooping a lot

Stomachache : Being constipated can cause most of your symptoms but not the weight loss. However, a stomachache in the upper abdomen that shoots to back, weight loss and odd-looking stools may indicate a pancreas problem. Please see your doctor asap.

Agree with Dr. G: Unintended weight loss always warrants an evaluation. It is not feasible to provide a meaningful opinion without additional history, physical examination and may be some tests. It would be prudent to see a doctor, preferably a gastro-eneterologist.