Diane, I don't have that problem. I have had major surgery, though, and didn't notice my pain being any worse. Actually it was a little better because they had me on Darvocet for several weeks after I returned home.
Here is a link that might help you, though, if you are concerned about more pain with fibro and surgery. Hope this helps you.
http://www.prohealth.com/library/showarticle.cfm?libid=14089
Sherrine