This is the owner the of the pale hen. I thought I would put an update here for any future viewers in case they were having similar problems.
We separated my old English game hen, Pip, from the flock during the daytime with a couple of hens from the big coop in their own little run and kept a close eye on her, giving her some special food and lots of attention. She still didn't seem well for a little while, but then she seemed to pick back up again. She still did not lay any eggs.
Unfortunately, her condition went downhill again. Last Thanksgiving, she seemed to be dangerously ill so we took her to the vet again. It turned out she did have anemia. She also had a loud heart murmur and a mass that could or could not have been cancerous growing on her left side, near her vent. We discussed different treatment options and the possibility of euthanizing her if she did not improve, and finally decided to try giving her a type of antibiotic to see if it would sort out the heart murmur. We also gave her another medicine to help her blood circulate properly. The vet told us to keep her inside all the time with a heating pad in her basket. (We bought a waterproof one and put a towel over it so that Pip would not burn her feet.) She was underweight so we were instructed to give her whatever kind of food she wanted (rice, cottage cheese, greens, etc). The vet told us to return in a month to see if she had gained weight and to check on the size of the mass growing on her side. If it was cancerous, then it would grow quickly.
Pip had not had a very good appetite, only being tempted by things like mealworms, but by mid-December, she started eating other foods with eagerness. Her face and comb became redder again and she grew livelier. I was happy and hoped for good news when we returned to the vet.
The heart murmur was much quieter, and the medicine had helped with the anemia, but the mass did turn out to be a cancerous tumor. It had grown at a quick rate since the last vet visit. Just about a month after the second vet appointment, she passed away. I was very sad because she was the friendliest, sweetest little chicken I have ever had. But she was always lovely and happy, right to the very end.