Leg weakness with Sertaline

Hello,

I have been suffering with random arm numbness since starting working. For some time and had done a MRI with no abnormalities all healthy. I have been suffering with bad arm numbness in both arms for months and was given sertaline. As the condition may be neurogenic from my doctors advice

The question is now I am getting bad muscle weakness in my legs and body. Like jelly legs and do feel tingling around my neck 

Provided for anxiety