Jon, I'm like Gil. Did not realize you had a full blown case. So sorry it happened to you, and especially at this time of year.
We are in the same boat with the weight loss and weakness. I lost 20 lbs. of muscle while in the hospital for three weeks, and am on the road to getting it back now. I've gained about 4-5 lb. back in three weeks at home, and getting stronger every day, in very small increments. Going shooting tomorrow for the first time.
Hang in there, eat heavy on the protein. My GP told me that is what will build the muscle back quickest, and stay active. Push yourself.
All my best, SRH