I replied the same to a similar thread. I also had a weak left leg after my last relapse. Got much better after the 5 days on corticoids in the hospital but still felt the weakness. What I have been doing since then is… first walk and walk and then run and then run larger distances and while I still feel that the left leg tires faster than the right one, I keep running and I keep getting better and stronger.
I might be wrong but I think that giving up because the weakness or pain is what really makes us feeling worse, as we get into a downwards spiral where you feel weak, so you don’t exercise so you feel weaker etc. Fighting against the numbness, weakness, etc is what makes us stronger.
Do not let MS beat you, and even if you feel it’s beating you, at least fight so it will be much slower than “it” wants and slowing it down also means we are partially winning the battle.