It may not be true that you have no reason. There could be things that you don't realize bother you. Maybe low self esteem, not getting your needs met or something else. There could be physical things causing it like thyroid problems, or vitamin insufficiency. Have you went to the doctor recently and talked to them? They can do some blood tests pretty easily to know if it is a physical problem.

Have you tried therapy? Or maybe Anti-depressants.

I wish you like in struggle.