I think I have split personalities or multiple personalities

I feel as if I have multiple personalities. Whenever I am put in a certain situations certain parts of me outweigh my 'original self'. If I am annoyed or provoked to be angry then that part of me(can't say the name, because of possible relapse) becomes very difficult to calm down/control. There are times I become randomly happy or have uncontrollable laughter at the MOST awkward places and time, most people aren't laughing at funerals or smiling without something funny being said... However it's difficult to address my personalities because every time I attempt to acknowledge anything, I get an overwhelming migraine, as if my own mind doesn't want me to solve the current "issue" going on.
Now several years ago(3, maybe)I felt as if I shouldn't leave my personalities be fully apart of my main self(the upfront self), so I "suppressed" my emotions, which in the end backfired. Because now I think my personalities found a way to express themselves, despite me ignoring them.
Now I am kind of stuck "dealing" with violent daydreams and dreams of taking revenge on former friends (from YEARS ago) from one of personalities, and being stared at in public because I laughed at an inappropriate time.
I am probably just rambling on, but... I lost my train of thought again..

Sounds like a lot going on. Is there anything in particular you'd like from us? Nobody on PsychCentral is supposed to "diagnose" anybody else. For me personally I've had some experiences that sound somewhat similar. And from my experience seeing lots of therapists over the years, I would look for a therapist who specializes in this kind of thing.