Hi VapHer!
I'm a suspected fibro sufferer as well, doctor doesn't want to outright say that's what it is until he's got nothing left to go with, but he's mentioned it every time I've seen him and I've gone through a few meds for it. Anyway, when I switched to vaping I was still smoking some. In the beginning I did notice more pain on days I smoked less, I also noticed more dehydration. So more water was the 1st thing I tried. It helped some. The longer I was vaping, the less I was smoking, and it all finally started to calm down. Now I've been vaping for almost 2 years and not smoking at all for 15 months. My flares and general pain evened out to my "normal" range and frequency after I bumped my nicotine level up to 30mg for that final few weeks of quitting smoking. I think it's what finally allowed me to quit smoking too. I went back to a 24mg level after finally quitting and everything is back to my version of normal pain wise.
You do have to remember that most everyone goes through some sort of withdrawal symptoms when they quit smoking, even if they are now vaping. Those symptoms have a wide range and I've noticed that new issues/symptoms are more prominent and harder to deal with than the ones we are used to having on a daily basis, so it stands to reason that dropping the cigarettes is the problem here. That is a lot of chemicals you are no longer getting so your body has to get used to the change. So keep at it!! It will even out eventually.