Mental Health

I feel like I am losing my mind. About a year and a half ago I started having problems with my memory, like remembering my past, past events, things that have occured in my life and such. It's seemed to get worse and worse over the year, my head hurts all the time, I can't conentrate on anything, I've lost my math skills, I feel like I'm going to lose my ability to do things and talk eventually. I feel so stressed out it's unbelievable, and when I try to keep my mind on sonething else, I can't. I've been to quite a few doctors that ran various tests and everything came back normal. I don't know what to do anymore, I really need suggestions. :/ Please. Anyone.