Hi Trindz68,
Welcome to PC!!
It comes and goes for me, too. You may think there isn't a reason but even something like an anniversary of something that happened a long time ago can trigger it from your subconscience. Or it could be something else that you aren't aware of. I think that's apart of the cure-trying to figure out what the cloud is made of.
I'm sorry you're feeling so heavy and weary.
Hugs!