I have no idea what's wrong with me

So I have no idea whats wrong with me... since I can remember I've had major mood changes very regularly where I am extremely ecstatic and determined and on the top of the world, and then someone will say one thing which will make me want to cry, and I usually do. I feel like I keep breaking down. I'm under a lot of stress but it's just the career Im in which makes everything very unsure, but then to be honest I couldn't ever be in a normal career when things are certain all the time. I feel like I am extremely complicated and I don't even understand my own mind. I wish I could just relax a bit and just have an easy life but I am my own worst enemy and sort of self destruct myself all the time. Plus I can't ever go to sleep, it takes me so long because my mind is spinning so much. Urgh it's just really starting to get to me and it's making my OCD really bad lately too