Hi and Welcome to NeuroTalk, Thisiswater..
There are quit a few, here, who were DX in their 50s. Most can think back to a time in their youth, when they may have had MS symptoms.
I have a double DX...I was DXed at 35, as a result of an LP (myleogram) went into remission and deniel and then DXed at 53, when MS rose it's ugly head again. My 50s is when it hit me the hardest and stayed around to do it's damage..
I hope your Doc is wrong and your ON clears up an goes away..
