I have this same thing. My CT scan showed "hydronephrosis" which is a backup in the ureter/kidney. Essentially, my endo is pressing on and partially blocking a ureter. My symptoms are just what you're describing. Burning...kind of a dull ache in my side and back. Also bloating. I'm wondering if yours isn't bad enough yet to show up on their scans. I usually feel things before a lab or scan will detect it.

I've has this. Could be kidney stones bc a cystoscopy only shows inside the bladder not the kidneys..unless u had that procedure too. I get chronic kidney stones and my lower back back and side area abdominal will hurt like crazy when I have one. Only way to really know is a CT but the stones will only show up if they r at least like 2mm I believe. I'm actually currently dealing with passing a 5mm one. Let me know if you get sharp pains too in those areas. But my kidney will burn really bad when I have one especially when I push to pee or poop. Hope that helps some. Another thing possibly an entrapped nerve from a surgery. Have u had a recent one?

I have has a cystoscopy 4 years ago and that didn’t show anything
I can’t wait for my appointment on the 19th
I have been dealing with this pain off and on for a few years, this time it’s back after 4 years

I have had 2 CT Scans in 2018 when the pain first started but they didn’t show any kidney stones.
My pain has come once a year and it has a mind of its own.
It hurts deep inside and in my back.
A burning sensation and bloating.
I haven’t had laparoscopic surgery yet.