I've been struggling with similar stuff for the last year and a half. I do see some connection to the general level of ME/CFS severity, but haven't been able to correlate precisely. First identified as the culprit (via MRI) was a really messed up lumbar spine, but injecting that with some terrible steroid did nothing. Then a few spine surgeons weighed in and a wise one suggested it might be my SI joint that was problematic.
I finally had PRP injected to the ligaments attaching to the SI joint and intensive PT with a person who specializes in pelvic floor pain and dysfunction. Five months post PRP I am free of the pelvic pain 98% of the time, and the bloating has stopped mostly. SI joint and sacrum still hurt, but at a much more acceptable level. I can lie on that side at night without gasping in pain. I have painstakingly strengthened that leg and am now able to walk without too much grief, though I still have to ice the area after any amount of walking to keep it from inflaming.
During this process, I have become aware of how relatively clueless spine doctors are about the cause of the pain they treat, but I did want to report a modest success in addressing my situation, which sounds very similar to yours
@belize44 and yours
@tinacarroll27. I believe the success came from isolating the source of the problem (in my case, SI), treating it (I did a dexamethasone injection to the region first and it was brilliant for about two weeks, confirming that it was a cause), with PRP, and getting PT which from someone with the expertise and education to work with precisely the affected parts of my body.
Wishing you good luck,
@belize44. Are you doing anything about it right now? Any plans or appointments to see to it?