I need help.

I am a student in my last year of studying biochemistry. I am doing a 10 month internship/project at a lab. However, my mentor seems to have two 'personalities'. 

One personality is euforic where he sings and dances and is overly happy and compliments my work a lot. When he is in this mood he acts as if we're best friends and then he tries his best to get to know me on a personal level.

His other personality is mean and angry and overly critical where he insults me in my face. He gets extremely impatient when I make a little mistake or when I forget where HE put something or when one of us gets lost in the building. When he is in this 'mood' he seems to try to put me down as best as he can. When I tell him I am trying my very best he says that I need to try harder and that I will never get a job with how badly my experiments go. The comments he gives me are also not useful at all and only put me down. 

He can switch from his euforic personality to his overly critical when he thinks I am not paying attention to what he says and does. I don't know if this is important but he is also extremely energetic the entire time. 

I don't know what I can do about this situation but quitting is not an option. 

If you have any advice, please reply.