I have all the problems you describe re the left buttock. I had a test on the pudendal nerves and got a diagnosis of left pudendal nerve entrapment. This nerve lies adjacent to the perineal area between the vagina and anus in women (same area for men) and I had severe burning pain here. Only an ice pack stopped the sensation of burning even though the nerve is not “hot”, but your brain tells you it is. This condition sometimes affects cyclists, although that was not my history. The only thing that finally got rid of this pain was a spinal cord stimulator. The SCS is effective on nerve pain but not so much on muscle pain directly. But I am so thankful for getting rid of this particular pain and am now working with the SCS rep on intensity and placement to reduce other nerve/muscle related pain. I have gone from being in bed most of the day to only brief rest periods. Also, my posture is improving since I no longer feel like I need to slump forward. When I get up in the morning, I am hopeful again and goal oriented instead of feeling dread. I do take Lyrica and Cymbalta but don’t use opioids b/c while temporarily effective, I think that in combination with the impaired pudendal nerve, it was what caused occasional loss of control of my bowels. With no opioids, that problem disappeared. I hope you find this information helpful.