Nana, you could have both but I hope you don't. Usually an MRI is ordered to see if you have lesions on the brain before a diagnosis is given. I had a friend whose doctor told her she might have MS and she freaked out. Turns out he was wrong. Doctors should not throw out these terms to patients. It's no skin off their nose because it doesn't affect them but it's far too stressing to tell a patient when they don't have all the facts!
I can have weakness in my arms and legs but I have back issues and fibro, too. I'm weaker than I used to be because pain has caused me not to do things like moving the piano, which I did by myself every year during spring cleaning! Just lifting six plates into the cupboard has a difficulty factor to it for me. So, don't start projecting yourself in the future. The bottom line is that they really don't know yet and they could be wrong. As we used to say, don't buy trouble!
Let us know what you find out because we really do care about you.
Sherrine