My hair is completely ruined, I don't want to go out anymore

Hey girls, hi! For the past few months, my hair has been falling out in handfuls no matter what I've done. When I look in the mirror, it really feels like my crown is thinning, and seeing those girls with thick hair on Instagram totally gets me down. I used to have thick hair, and now I’m left with something that looks like a rat’s tail. Has anyone experienced this and found a solution, or is everything just completely psychological? I just don't know.