Fab, you see this is where I am confused with all this anxiety stuff, I feel like this about about a lot of my symptoms too - I do think you have a lot of anxiety and stress, but I don't think it should cause you to wake up in agony. Its too easy to put everything down to stress etc (I found that myself too) and miss other things that are going on.
I wonder if you have some kind of muscle sprain that is causing this pain. the great thing is that your breathing is ok, so stay calm and keep breathing slowly. Maybe try and have a hot bath and put some more deep heat on (you will stink all day though
)
I hope you feel better as the day goes on.
Burning
hope you are ok too, will reply to you later.