low fat diet for sure. but definatly get it checked out severe pain after a surg could mean a lot of different things from infection, to some tears , get it checked out
Almost forgot, you may want to consider following a low fat diet. You may not be able to easily digest fats after GB surgery.
You need to find out whether any sludge or stones may have gotten into the bile duct during the surgery, or if you're having spasms of the bile duct following the surgery. Call your doctor and don't let him/her tell you the pain you're going through is normal, or that you're just 'adusting.' And the fact that you've got a fever says that something more than normal is going on.
You are actually having a 'gallbladder attack,' unfortunately, and taking narcotic-based pain meds is not going to help. In fact, narcotic-based meds can make things worse.