I've been aware of my fibro for about ten years now. Mine's been really well controlled (pain-wise) and doesn't seem to be worsening. Thankfully. My symptoms are more GI and mood related with an underlying level of ache and muscle pain.

As far as a cause I've become convinced there is a major connection with childhood abuse and neglect and PTSD. There is good research behind this theory but of course you can't prove causation.

As far as exercise the best thing I've found is no impact deep water aerobics...though I'm not sure how that would affect your skin?

I also identify with your feeling of not really wanting to share your diagnosis. Even now it feels like a bit of a 'cop out' diagnosis.

Hope you continue to find useful resources.