I know that this post is nearly 4 years old, but OH MY GOD THANKS BRO!! I currently have a Skyrim Special Edition 50 hour character which had the same reoccuring bug OP described (I usually had 4-5 autosaves ready in case the bug hapened and would change back) but now I didn't notice for some time and there were no saves to go back to because of it. I don't know how I found this post it was a miracle because I was already going to give up on this game. Your suggestion fixed it all - no incomming damage, no shouts available etc.
