Ugh, that doesn't sound very pleasant at all.
I'm not sure I've had quite the same feeling, but I've been in states where I just wish I could shut my brain off.
I'm not sure if it would help you, but one thing that helps me is to put on headphones and listen to and watch a movie. I'm not sure why, but the headphones seem important. I think they help me to focus or lose my self in the movie. Without them I just start thinking again.
Sometimes a bath in the dark is good, as I find it calming. If you're too hot, you could make it cool.
Other times, I just go to bed!
If you're too hot, can you put a wet towel around your neck or something similar to try to stay cool? Remember to drink lots of water in case you're getting dehydrated.
If you're really feeling like you're at breaking point, I think you need to ask for help. You don't need to be suffering like that on your own. Is there somebody you can call for help? Maybe a therapist you can see? Or a doctor? Please don't hurt yourself.
No diagnosis, lots of opinions, and a bunch of issues that I haven't quite figured out.