My 2 1/2 year old BR hen is sick. I brought her to the vet and she is on medication now. She is SUPER skinny, which I guess is from being sick. The vet weighed her and she is just about 3 lbs, while my other BR hen is around 6 lbs. She is drinking a lot and taking some pecks at her layer pellets. How can I get her to gain weight? Should I wait until she finishes her meds to start plumping her up?