Can't be happy. Minutes of fun & im sad.

I'm not happy at all. I'm sad all the time without a reason. I laugh at jokes, but the next minute I'm sad. I don't want to be happy all the time, but I want to stop this sadness. I go out with friends, but I want to get away from them within minutes. I never used to be this way. I'm not able to remember anything. Sometimes I forget the name of my family members, and can't answer any question asked without thinking for a long time. The happy person everyone used to love is not around. I'm not myself. I can't complete a sentence while I speak because I forget. I used to be an inspirational speaker on stage. I don't know why my speech rate has become worse like my memory did. I was happy by myself, writing, sketching, shopping by myself, but now I'm very dependent on others. I skip bathing for days straight. I skip meals for days. My mind is a buzz. I did all efforts to be happy... Playing, reading, being with people, meditation, singing... It's the just few minutes of fun & im sad.