Also, people with MS often have a hard time with nouns in their speech - not being able to identify objects, or calling it by the wrong noun
. TV instead of fridge, for example, or microwave instead of oven. Sometimes it's in the same category. When I've been really bad off, I'll tend to call things by another word that has some of the same letters.
Your back numbness is an indication of something, possibly a pinched nerve. However, it could also be a lesion in the spine.