Mike, I agree that you should have called with something that unusual. The only thing I can think of that might cause that would be if the catheter that was used to drain you was held in place with tape that irritated your skin. I am highly allergic to all surgical tape and get burns from it, which is why I immediately thought of that. It does seem to be an external or skin problem. When I recently had a deep oozing, burn-type wound on the inside of my upper thigh after surgery, I thought it was from tape, but it turned out to be from the compression stockings. The Mayo dermatologist I saw told me to get some zinc oxide and use that on it until it healed. It took months, but finally did heal. Zinc oxide does heal external wounds and is available in a tube over the counter (very inexpensive), so you might want to pick some up tomorrow and try it. I don't think it can do you any harm. Then call the doctor who supervised the procedure on Mon.
Glad you are feeling some relief in your stomach.
Hugs,
Connie