As crystal lady and Claritytoo sugest, Not all mental heath workers are familiar with the effects of trauma, or the treatment of traumatized people.
Many do not even believe in DID/MPD.
definately look for someone with trauma experience, and even experience with dissociative disorders if you can.
My therapist says, some places(and people) speak DID. and others don't. it took a long time for me to be able to admit I was having these kinds of experiences. I'd been holding them back, and deny-ing them for so long I literaly couldn't speak. be patient with yourself. and don't jump at diagnosis.