Chicken not responding to meds

[TracyandEmori]

Hi everyone! I have a chicken (approx 4 yrs old) that started to show signs of illness: slow, not keeping up with the group. After examining the flock's stool I saw a couple of worms (cannot say if the wormy stool was hers or not) so treated the whole flock. After treatment she started with very runny stool...stool stuck to her feathers, et. So I treated them again approx. 2 weeks after the first treatment (diatomaceous earth). She would rebound a little but ultimately go back to lethargic, drinking a lot (due to dehydration from the runny stool I'm assuming), so took her stool in to vet. She was diagnosed with Coccidia was treated by vet for 5 days. She again rebounded in attitude but the runny stools continued, and I'm talking watery stool..no shape/consistency to it. She has lost a lot of weight as well by this point. So after waiting another 2 weeks after her vet treatment I went ahead and treated the whole flock with Corrid (7 days). She again rebounded but still continued with the runny stool. It is now 7 days after the Corrid treatment and she is back to being slow, quiet, not really pecking around like a chicken would. So....anyone else have an issue like this where a chicken only rebounds for a few days but then ultimately reverts back to not well and continues to have very runny stools (we are talking about 2 months of this now). I have drenched her, added electrolytes to water and also include yogurt off and on through out this time period. Diet hasn't changed, coop is clean, they have a very large yard and are also let out daily on to our 3+ acres (live on 60 acres but they only go around the house). Oh...she also continued to lay pretty consistently the whole time until this past week or so.

 

[Eggcessive]

I thought that she might be suffering from internal laying or egg yolk peritonitis at her age from the earlier symptoms, but if she is laying regularly, that probably is not the issue. DE will not treat worms, since it becomes useless when wet inside the body. But since you had the fecal float, their must not have been a worm load or the vet would hopefully have seen it. Cocci infection in an older hen shows that she may have some immunity problem. Using probiotic plain yogurt 1 tsp per chicken in her feed twice a week may help. Diarrhea seems to be a common problem, and could be related to how much she drinks and what she eats. Their could be a problem with enteritis which can follow a chronic case of coccidiosis. That wold require antibiotics, and you probably would not to eat her eggs afterward, or at least without a period of withdrawal. Your vet could do a gram stain on her droppings for a diagnosis. Valbazen 1/2-3/4 ml orally and repeated in 10 days, would be a good worm treatment for most all possible worms in the future. She could be just slowing down due to her age. I have mostly 4, 5, and 6 year old hens and have quite a few like that. Below is some info on enteritis:
http://www.thepoultrysite.com/diseaseinfo/101/necrotic-enteritis/
https://www.merckvetmanual.com/poultry/necrotic-enteritis/overview-of-necrotic-enteritis-in-poultry