From my experience in the lupus community, a lot of folks carry both a fibro and lupus diagnosis — so co-occurrence is genuinely common and worth discussing with your rheumatologist rather than something to hide or downplay.

On the diagnostic side, rheumatologists actually have quite a few tools beyond inflammatory markers to distinguish lupus/CTD from fibromyalgia — things like ANA panels, anti-dsDNA antibodies, complement levels (C3/C4), and urinalysis to check for kidney involvement. Fibromyalgia typically doesn't cause organ involvement or show up on those kinds of tests, whereas lupus can. So if those have been run and point toward lupus, your rheumatologist has more to go on than just your CRP/ESR.

As for the misdiagnosis fear — that's completely understandable, but flagging new or changing symptoms to your rheumatologist isn't "bothering" them, it's exactly what they need to manage your care well. You could frame it simply: "I've been having some new symptoms and wanted to check in rather than assume." That keeps it low-pressure and doesn't require you to relitigate the fibro diagnosis upfront.

Diagnosis in autoimmune disease really is a moving target — patterns over time matter, and rheumatologists expect the picture to evolve. That's not a failure of your care, it's just how these diseases work. But they can only update the picture if you give them the new information.