When I broke my leg back in the 70's, I lost 50% of the muscle mass in the leg in a few weeks because it was in a cast. It is normal for the body to absorb muscle tissue when the muscles aren't being used (I believe they call this atrophy). I have lost a lot of muscle mass just be being in bed so much. I am a little under 3 weeks away from treatment (rad/chemo) and am only out of bed a few hours a day. I am slowly getting a little more energy every day.
And, also, I have had days where I throw up all of my pills also, have a hard time keeping water down - radiation sickness??