I've had exactly the same issues. But It was acknowledged that Femara is the cause.
Asking for help I was dismissed & told its my choice take them or risk recurrance if I don't.
Its the usual answer from all the oncologists. I was told by 3 oncologist "I can NOT advise you stopping AIs."
I've asked repeatedly what can be done to stop or reverse the imense femur bone pain in both legs that's being caused by Femara (Letrozole) & what are my alternatives to stopping..Can they stop.my deuteriation.? I'm.on high dose calcuim & vit d already. They seem unconcerned with my pain saying take MST morphine !! .

One oncologist in London uk
said try Tamoxifen 5mg or 10mg ( as its known to be less invasive on bones & pain)
20mg is the standard daily dose
Another oncologist said at a uk.hospital we do not prescribe low doses at our hospital.its unrecognised.
Another said just STOP all AIs & take the risk & enjoy a better quality of life.
Basically oncology do not have a medication that does not cause joint pain, bone pain & muscle pain so those of us who suffer this it's a total nightmare.
Like you I've seen orthopedic consultants as well as rhematogy consultants. Both confirmed my arthritus & fibromyagia is NOT causing this bone density loss& pain & both confirmed it's definately the AIs.
I've tried Tamoxifen
Anastrrzole, Examastane Letrozole & Anastrazole. All gave me severe pain issues.
We need a new medication & more research asap.