The reason they say NOT to donate blood is they really don't know what causes Fibromyalgia.
I was d'xd with Fibro back in 1999. The drugs of choice then were antidepressants. I tried 5 of them & all gave me nothing but major side effects. I've tried the newer drugs & again major side effects. So I take vitamins, exercise & try to eat as healthy as I can. One bad days my Husband massages my muscle knots. If I push myself I know it will take me a few days to recover. Trips in the car exhaust me, again taking a few days to recover. So I try to plan those all day outings & keep the next few days open to recoup.
They say Fibro is possibly triggered from some underlying virus. Looking back I had a nasty flu type virus that attacked my muscles (mostly leg) 10 years before I was d'xd with Fibro. I had muscle spams from lower back to feet for 3 weeks, fever, nausea, etc. 2 rounds of antibiotics & a couple months to get back to feeling normal.
The hardest part of having Fibro is having everyone, including your doctors, tell you, you look healthy & normal. They tell you to suck it up. I even had people, including my cancer docs, say that to me while I was going thru chemo. I don't know what you're supposed to look like. If they had even one day of Fibro they'd change their tune in a heart beat!