Has anyone else dealt with this? Is it fibro related or something else?
I keep having issues with a rash on my upper chest area. It is not covered by my bra, but begins about there and extends up to the collarbone/neck line area. It is not covered by any tight clothing. The rash is mostly flat or slightly raised, reddish bumps. It will flare up for several weeks, then disappear for a time, only to return again. Sometimes it itches, sometimes not; when it does it drives me nuts.
I haven’t changed anything like soap or medications, and haven’t been bothered by food allergies.
I’ve had a similar rash twice this year on my legs, arms, and neck. Stumped my docs but my primary diagnosed it as autoimmune related to Fibromyalgia. I went through 2 courses of prednisone which got rid of it but left me fat and depressed!
Well, maybe I’ll just try to live with it then . . .
I don’t need anything else to contribute to the depression - I’ve finally gotten a really good handle on that and don’t want to mess it up and heaven knows I don’t need any help with weight gain . . . 
I had that problem too. I ended up going to a dermatologist. They took a biopsy from several spots. I guess I’ve been taking some medicines for so long I was developing an allergy to them. So I can’t take statins, metformin, and Aleve. It was a long process of elimination.
Turns out that was only the half of it. My liver enzymes were getting all out of whack. Another biopsy (that was the biggest needle ever! 
) later, I have autoimmune hepatitis.
That could also be what caused my rash. My primary doctor thinks it’s more of a compilation of all of it.
You might want to ask the doctor if they can get a full panel blood test done. That was what my primary care doctor did. Then he sent me to the dermatologist. Over the next year or so he kept an eye on regular full panel tests. Amazing what he was able to learn just for a blood test.
Trust me I could be dead now if my doctor hadn’t done all that testing. So don’t try to just live with it.
Have you been tested for shingles? I was hospitalized last fall with a breakout on my body. They said it was a type of shingles but I can’t remember now what it was called but I just thought that I would mention it.
As a retired dermatology nurse(and someone living with fibromyalgia) I strongly recommend seeing a dermatologist. Rashes can have literally HUNDREDS of different causes. Anytime something starts near the bra area the first thing I’d want to have ruled out is yeast… the same thing that causes “athletes foot” can happen just about anywhere on the body. And YES, it can come and go like you describe here. An easy thing to fix, too.
For the record, I’ve never personally developed rashes that were caused by fibromyalgia. That said I have exceedingly sensitive skin and a great many allergies; which I DO believe are common to the fibromyalgia profile.
Best of luck to you!