Am I fit to work? It always feels like I want to go home everytime I arrive at work. I get really depressed.?

I feel that Im abnormal. I get so tensed with bosses around. I feel so stupid and I always forget things. I get really sad then happy the next minute. I used to be driven in life. I even graduated *** laude but now Im the total opposite and I am so inconfident at work. Is there something wrong with me?