My Dr. said the same thing...NSAIRAB interfere with bone growth so they are a no no. They said only Tylenol.
If you are done with child bearing and you are having bad cramps, you might talk to your GYN about having an Endometrial Ablation also called NovaSure. The procedure basically eliminates the lining of the uterus. Its outpatient and similar to a D and C. I had mine 3 years ago and havent' had a period or a cramp since. One less thing to worry about if you are planning to have back surgery. Also, many insurance companies have an out of pocket max. so if you have them both in the same year it could save you some money.
Glad I didn't have to deal with that during my recovery! Otherwise, I would have used the stick on heat paRAB that others have mentioned here.