Yeah, I've had CFS for several years and just this summer started getting an odd tingling, numbness, and ever-so-slight redness/swelling on my lips and tongue. Nobody can figure out what it is, as it doesn't resemble anything that would normally occur inside the mouth. My dentist said that it's almost certainly some kind of virus, and that his first suspicion would be that the CFS is viral in my case and has decided to spread to my mouth recently.
I don't know that it is common, but it certainly can be one of the symptoms. There are so many symptoms related to fibro...I could only begin to list them here...I think I would run out of space. The prob. with fibro is that there are so many overlapping conditions. It's endless it seems.
I often get numbness on the side of my face or down my jawline. It goes away and returns another day. There are days that my hair actually hurts (it's really my scalp). It's a lot to take in, but then so is CFS/GWS/MS/Lymes. We run right along with them.