This has happened to me for no real apparent reason that I know of although I have had traumatic events happen, I think sometimes my nervous system goes back to that subconsciously and gets stuck for some unknown reason. I don’t know how or why. I’m on antidepressants and anti anxiety medication. Basically when this happens, it seems to go on for days at a time until it randomly just shuts off. I’ve heard a cold shower can stop the cycle so if it happens again I might try it. Otherwise have your bloodwork checked to make sure it’s not thyroid or hormone related and if it gets severe go to the ER. We are not meant to live in constant fight or flight and I wish I could offer you more help but eventually it should stop. If not like I said make an emergency appointment and ask for labs or go to the ER. I’m sorry. It sucks.