It could almost be anything, colitis, ulser, gallstones, I would see a doctor now before it get worse.

I am female currently going through the same problem. I have a constant left side ache right under my rib cage that radiates into my lower abdomen and back. They just found that I have a "wheat/gluten" allergy from a simple blood test. Now I have to have an endoscopic exam to check if I have "celiac disease." I guess this can cause a lot of gastro problems due to the allergy. 1 in 133 people have this. Four years ago I had a colonoscopy, ct scan (kidneys & abdomen), and anything else you can think of for the same pain and it would come and go. Now it doesn't go anywhere. I just started taking zelnorm for ibs 7 days ago. Can't tell yet if this will help, it hasn't so far. I also have a adhesions around my colon which could be the problem, but now with this wheat thing, they are looking in that direction. I hope this is of some help to someone.