What you are feeding her is not a balanced diet, and it does not have enough protein. You would be better off feeding a layer type feed or a flock raiser feed (plus crushed oyster shell available for free taking.) Her diet probably has nothing to do with her illness, but your chickens would be healthier. Fowl pox which is spread by mosquitoes, lasts about a month to 6 weeks. I would place her back in the coop in a dog crate with food and water, so that she feels more comfortable, and possibly will eat better. When I have one who stops eating, I try and tempt them with a little scrambled egg or canned tuna.