Has anyone dealt with sit bone pain as a result of less fat / lost muscle mass in the butt?

I’ve been working through sit bone pain for almost a year due to hamstring tendinopathy (per the MRI). PT, Ice, ibuprofen, active release technique (ART), new seat and bike fits haven’t helped. One orthopedic surgeon recommended staying off the bike! Nope.

I described my situation to a highly recommended sports orthopedic surgeon. In short, He said to EAT more carbs / protein and do butt exercises. Gotta gain weight, normal for my age and current weight. Flat butt!

Needless to say I was floored as I’m only 64 years young and 165 lbs, BUT I’ve lost 15 pounds since retiring 2 years ago, not by design, just don’t stress eat between meetings anymore, no meetings!

Curious if anyone else has dealt with this situation and what they did to get back on the bike?

Thanks!