My hair is literally falling out in handfuls, I think I'm going to go bald.

I've been crying in the bathroom for the last two months. Every time I brush my hair, the brush is overflowing. I don't know if I have a health issue or if it's just stress, to be honest. I had blood tests done, and nothing came up, but it really feels like my hair is thinning. I can't even look in the mirror anymore; I'm really down about it. Is there any solution for this?