I also had a frozen shoulder (twice iirc, though usefully my online record is not helping me much!), it was both annoying and painful at the time ( I recall not being able to reach to the small of my back, though quite why I needed to do this and remember this being a problem so vividly I don't know, perhaps I had a secret desire to audition as a cowboy with a revolver in the back of his waistband!).
I went for physio, and was discharged without it having got all that much better (which is similar to what happened with the rehab post-scaphoid fracture and cast for 12 weeks, though to give the physio their dues this time around I think frozen shoulders often just need time, wrists need more challenging targets - 45deg from vertical isn't that imho, but I digress)
It did resolve itself and I don't recall it being a massively drawn out thing. It's hard to know whether it resolved itself simply due to time, or due to my pure bloody-mindedness and repeatedly forcing it to move into painful positions (which is what I had to do for my wrist post-scaphoid fracture and post-discharge - I was quite used to making parts of my body hurt in the expectation they would then get better and that it wasn't in fact doing any more harm, which was certainly the concern I initially had with my wrist).
My shoulders can certainly be stiff these days and I don't think I have the same range of movement that I did as a twenty year-old (I can touch my fingers behind my back, but I can feel I'm doing it and I certainly can no longer hook them together), but I apparently gave them (my shoulders) a bit of a hard time in my twenties doing martial arts (shoulder locks), so it's probably to be expected.
I'm not sure that helps much though, sorry!