Welcome to the MS board, Terri..
I was DXed in 1974, by my PCP, with PN but he sent me to a Neuro for a 2nd opinion and he DXed me, in '75, with MS, after many tests in the hospital..No MRIs then.
I have learned from others that PN & MS go hand in hand a lot. So you may have both?
BTW, I'm your Momma's age..