Yes and no. (wacky thing this MS)

Doing stretches and exercises as long as you don't push too hard can help keep muscle strength up. I try to do some lite yoga, or at least some of the stretches from the download on the NMSS website.

Sometimes the weakness can come when you have pushed to hard and sometimes it can be a sign of something going on in the background. I get muscle fatigue when I push too hard, especially in my left leg.

Heat can make me into a ragdoll, so I always make sure I have some kind of cooling device if I have to go outside in high temps.

The being unusually tired leads me to ask if it's been hot in your area? If so, the heat may be causing everything to go wonky. If not and you have no fever, maybe give the doc a call to let them know what's been going on.

((((HUGS))) and hope you feel better soon.