5 weeks after rotator cuff surgery my shoulder wants to freeze up and is very inflammed. why?

Need PT: Most surgeons recommend physical therapy after rotator cuff surgery to help with motion and guide the success of a repair. Sounds like you may be developing a frozen shoulder. I would check back with your surgeon sooner than later.

Not uncommon: If shoulder is stiffening up requires more aggressive pt to maintain and regain range of motion. Can get inflammed and painful post-op which can lead to frozen shoulder. Usually at 5 weeks can still be worked out with pt.