Ok guys. i'm 31

about a week ago. i woke up at night like 2am or something and BOOOM

i couldn't move my shoulder. it was really painful.
This has lasted all these days and every night is the same thing. At daytime it gets a tiny bit better but then at night i wake up and reeeaally bad.

I get cramps when i try to move my shoulder in most ways.

What could this be? Could this be IMPINGEMENT?
Dr saw my shoulder in an Xray and said i didn't have anything.
He did say he would like to do an MRI but i dont have money so i said no.

He gave me therapy to do with a resistance band but i don't know if this is hurting me more and if i should continue doing it.