I have had a similar problem, pain and nausea after my gall bladder was removed. It turns out my biliary duct was damaged by the stones... before or after I don't know. A stone can escape just before surgery and they wouldn't know. The pain I was experiencing was from the damage to the biliary duct and pancreas. As CalGal said, get your enzyme levels checked (sometimes they are not acurate) and pay attention to what you are eating. Low Fat, as unpleasant as it is, is best! Small meals more often help as well.
Good Luck
You can still form stones after GB surgery, so they can continue to cause problems. In addition, you can experience spasms of the bile duct and sphincter. If you're still having pain, check with your doc and insist on being checked. Also have your liver and pancreatic enzyme levels checked. Some doc brush it off, don't let that happen.
And if you're not following a low fat diet, you may want to consider doing so.