Hi Kate- just saw your post.
I had my shoulder op in October and am just now starting to feel less pain in it.
Like you, I have fibro, arthritis in my spine.
My shoulder was pretty bad. I didn't have the tenodesis, but debridement of biceps tendon, also a lot of chondritis which was removed, acromioplasty, bursectomy, trimmed rotator cuff, which doc just last week told me was irreparable.
I am unhappy that the doc didn't tell me right away how bad the shoulder was and that it was irrepairable, also didn't tell me all he did. I would have been a lot more patient with the slow healing.
Vicodin and Percocet helped hardly at all with the pain, so I stopped them and went back to my tramadol, which helps most with my fibro. I was told to add NSAIDS for the swelling, which is just now starting to be resolved. I was told not to do PT until just last week, and then I am supposed to take it VERY slowly because of the extent of the damage.
The worst pain was the biceps spasms, which were just about constant and triggered by any movement. Two weeks ago the doc gave me a shot of cortisone in the muscle belly, which after a couple of days relieved that quite a lot.
I have just started, more than 3 months post-op, a few isometric exercises, which HURTS if I have ANY actual movement of the shoulder. The therapist does some passive shoulder stretches I can't do myself. I was lucky not to have a frozen joint. Since doc said I could do it, I did a very few of the hanging arm circles and used my shoulder for the least little housework, although dressing was very hard left-handed.
Your tenodesis is worse than my simple trimming. I was only in a sling 3 days, allowed to use my arm.
My point is don't give up. This just takes more time than what we are told.