Welcome, @russet3. Good question about whether adhesive capsulitis (Frozen shouler) cause nerve pain. I moved your question to this existing discussion:
- Adhesive capsulitis or frozen shoulder: What helps? https://connect.mayoclinic.org/discussion/frozen-shoulder-1/

I did this so you can read the previous posts and connect easily with members like @auntieoakley @artscaping @lioness @that_girl @jaysnh721 @Erinmfs @deanna2 @collierga @heather47 @anniebrook @drt @tsch @alive @deonmarie @vic83 @angie13. They may be able to share whether their experience with frozen shoulder also involved nerve entrapment or radiating nerve pain.

Russet, have you been to see a physical therapist? Might the issue in the sciatica be a result of posture adjustments or compensation due to the shoulder pain?

Hello @russet3 if your shoulder is pinching a nerve, the pain in your arm might feel exactly like that. I had some of that when my shoulder was at its worst. There is hope for healing. This might be one of the most painful things I have ever had, but it did get better. I started using Voltaren gel for a little pain relief, in addition to my doctor putting a steroid shot in the joint. PT didn’t start until it started to thaw on its own. The doc sent me to Pt for a consult but they said it wouldn’t help it until it started to move.
It was a long process but it got better and better. I still have some scar tissue that shouldn’t really be there limiting some movements, and muscle discomfort can be a thing but definitely nothing I can’t live with.
Has your doctor recommended a treatment plan yet?

Hello, I suffered from adhesive capsulitis after a humerus fracture and surgery. My arm was in a sling for weeks. Hence frozen shoulder. My orthopedic doc recommended manipulation under anesthesia. My physical therapist said she could get rid of the pain with therapy. So I did intensive PT 3xs a week. After a few months the issue resolved itself. Good luck. I know this is painful.