this reminds me of the man I used to talk to online. he would stay up really late IMing with me (England/US), we talked for hours, he would get giddy happy, then, sometimes would be in the pits of despair, one night he thought my avatar growled at him and he was being serious. I was told by people who lived around him that he heard voices in the rain and saw auras. they just thought that was him. I was told he was 'scary' because of his temper. he was all over the place emotionally, I knew something was wrong but neither of us knew what it was, I thought it was just depression at first and alcohol use. he was undiagnosed at the time we were talking online.

I would very seriously get your bf to a psychiatrist as soon as you can. Only a pdoc can diagnose him but it sounds like something that needs to be seen about soon. best wishes.