I Am So Emotionally Tired

I have not felt this emotionally tired in a while. I don't want to go back to that dark place, but I don't know what to do about it, because I don't know why I feel like this. Nothing changed. Not my diet, not my schedule, no one died. Nothing happened. Normally I would have guessed I might be getting my period, but I just had one. Why do I just feel like crying and crying and crying and not doing anything at all?