What causes severe mid and upper right quadrant pain?

I was going to say gallstones, but I guess you don't have your gallbladder anymore, and it would be unlikely that you have another stone lodged in your bile duct this far out. Other possibilities are a gastric ulcer, pancreatitis, or you could have a fluid collection where your gallbladder was (a bilioma, or a bile leak). I hope your doctor figures it out and I hope your pain goes away!