How do you go about getting an mri scan? do you have to have a special reason for one?

i battle psychiatric problems and am waiting for a second opinion. ive been told i have a personality disorder and that i have no depression or mental illness. but i disaggree i feel alot of my symptoms have something to do with mental illness. in the past i used to have trouble contoling inner rage, and still do have to fight to stay incontrol, but in the past, i would start to feel detached, and i would get into staring, unable to blink or look away, like in a trans. then i would explode. in public crowed places to. i really made a show of myself alot of times. i would act out and attack people, barge into them, knock people over. all this time ive been wondering whats wrong with me. im 29 now. this has been goin on since 15. presentley i suffer terrible low moods and have no energy. ive socially isolated myself. i have constant racing thoughts flooding through my brain that make me feel disorganised & muddled up. i have paranoid ideas of persecution. and high levels of anxiety