I'm a newby chicken mother with 3 hens, all 1.5 years old. My egyptian fayoumi is sick. She moulted about a month ago and never resumed laying. Feathers grew back in and she looked 'bigger' than she was before. Today, however, I noticed she stopped talking (normally very squalky) and has diarrhea with lots of yellowy poop on her bummy. Also had greenish runny poop in the nest (on one of the eggs I put in the nest as a suggested by someone else). Normally, they are fed table scraps and have pellets available to them all the time. They free range about once per week. Weather has been great except yesterday it snowed 4" and they stayed inside the coop all day. She is the dominant hen. She looked funny to me today-- somewhat hunchbacked so I went to pick her up today and she fell over running from me and just sat there. Her tail is typically very high with a proud stature, but today her head was saggy and her whole underbody seemed to be dragging underneath her with low tail. Since I'm new to chickens, I had a friend come over to look at her and she said she seemed bloated? I brought her inside tonight and made her an oatmeal, yoghurt mash and she ate it all up readily. Went to farm store and bought "quik chik" (vitamins and electrolytes for poultry) and also tetracycline hydrochloride powder but have not given her either. I've never wormed them. Other birds have also stopped laying (about a month now for all) one I think is moulting and the other has not yet-- both of them appear normal with no signs of mites or other parasites. I'm not sure what to do. I also need some guidance on the tetracycline powder (if you all recommend I dose her) because the ratio instructions are very confusing. I also don't know how to administer it. I bought a syringe to give it orally if you suggest that?