Could be something benign, or it could be pancreatitis, an ulcer, gall bladder
disease, bowel obstruction.... any number of things. Like somebody said above, if it doesn't get better soon, go to the ED. You can sit at home and guess about what's going on, and suffer with horrible pain, or you can see a medical professional, get some IV fluids and pain medication, and maybe some labs and imaging that can actually lead to a diagnosis. Just my 2 cents - free of charge