Hi mmoss I don't think what I have is same... have p.n. and now, apparently, essential tremors; but have a history of ibs-d, many uti infections from radiation cystitis; as long time ago radiation to cervix. But I do get every low pain and pressure pelvic areas and if have had a very bad day of fecal incontinence, I get SPASMS in rectum, vagina and bladder area... don't think can get any lower area than that, then it becomes legs!! .it happens only about six or so times a year very badly but many times on the verge.... but never sought treatment.
The rest of the time is almost daily lower and right side abdomen pain and if had lots of bm's then inside rectum but more a 'pressure' hard to describe. Only thing i found on internet is that the nerves in whole area are receiving wrong message from brain.......
As have many others on here, also had c.diff 2018 ... but as you and others describe your pain as burning, it does sound like something connected to nerves/nerve endings ... sorry i cant help but do hope you find a cause and relief soon..... pain is pain, burning is burning.... no matter where.... and lower pelvis is such a sensitive area to begin with. Take care, best wishes, J.