SO is manic depressive.

..P..
help 😕 
so a few years ago my boyfriend was diagnosed with manic depression. it was before we met. 
he went to California for a trip for 6 days and came back a completely different person. he is like in overdrive constantly. he can't focus on one thing and is constantly bouncing around. like can't sit still. 
he is opinionated which is fine but at my 12 week doctors appointment today he was so embarrassing and kept interrupting the doctor and asking questions that the doctor would try to explain and then he wouldn't even give them a chance to answer before he would spew off some other ridiculous remark or question. it was extremely embarrassing. 
he even changed his name on Instagram. he is extremely parinoid over everything. it's scary. last time he ended up in the hospital for 10 days. he recently lost a friend to suicide and it's really affecting him. I think that's what pushed him over the edge. I don't know what to do. it's like he's on drugs but he's not. it's his minds way of being depressed. it's crazy. literally. 
anyone else know someone who gets like this? and how do I help him??