Sick Barred Rock please help!!!!

I went to the coop this morning and my Barred Rock pullet, Dodo, was on the roost and I let all the chickens out but she was slow to come out. Her tail feathers are down and she's in a "ball" standing up. She pecked around very little and went back to the coop. She drank some water and stood at the doorway inside the coop. She pooped once and it was green. I don't have a very good picture of her poo because I was worried and looked for myself. She's usually the most energetic and fun but today she's not. I did spread some Sevin dust around yesterday and gave my chickens some potatoes and one of them drug one over in the Sevin dust. Do you think she could have eaten it and gotten sick from that? None of my chickens have had the Marek's vaccination but we're given medicated chick starter to prevent Coccidiosis. She's not disabled or can't move so I don't think it's Marek's.This is her poo. Not a very good picture though. I was watery too. They haven't been wormed either because I'm broke right now trying to buy food for 33 chickens. I'm selling some chickens today and I'll have some money. Should I isolate her from the rest?

I only gave the he medicated for a few weeks to my 3 I bought from TSC but I bought the Barred Rocks from someone when they were 2 months old. I don't know if she was given it or not.

And one more thing. Her poop wasn't ALL green. There was a lot of green but also some normal color (not much though).

Any advice???

Well I guess I'll start with wormer. I know my new chickens have worms. And lice. And mites. I'll look for Corid but I know I won't have enough to get that.

Wow. Okay. I really need advice here. It can't be too serious can it? She's drinking (haven't seen her eat) and moving.

She seems to be feeling a little better. I went to get some Corid, which I can't afford right now, but when I got back she was out of the coop and cleaning herself a bit. I picked her up and she feels like she's lost weight although she was just sick today. I put her down and she stumbled a little. She seems weak but she does seem better. I haven't found any more green poo but I did find some wet spots in the coop from where I think she's pooped. I'm going to get some Corid sometime today and start that. So does anybody know how to give Corid to a chicken? It's for cattle but I've read to give chickens Corid. I think she might have coccidiosis. Probably got it from the new chickens. Now please don't write me off as a bad chicken owner but I have very limited space and money so I wasn't able to separate the new from the old except for the new ones stayed in an outside pen and the old stayed in their coops. Dodo did fight with a new Barred Rock the other day. Could she have gotten Cocci from that?

How do I give Corid to a chicken?

Any help? I have given my sick chicken 1 drop of undiluted Corid and then I put some in the water. Not the full 2 teaspoons per gallon because I didn't want her to get too much Corid. I also sprinkled some vitamins and electrolytes in the water. She will eat bread and tomatoes and she's been drinking a lot of water. She seems weak and I can get some B2 if she needs it although I'm not sure what it's for. I've been reading about someone else's sick chicken and have learned all of this from that. Some of my other chickens don't seem like themselves. They don't seem sick like Dodo though. Her poo isn't totally green. It is becoming more solid but still the same amount of green. Is there something else I should be doing or giving her?

The first thing I want to mention -- you should NOT sell any chickens while you have sick chickens on your place. Think of it this way; You would be very unhappy if someone sold you sick chickens. Wouldn't you ?

Now for your chicken. She sounds like she mwy have coccidiosis. Dosage is 2 teaspoons of Corid per gallon of water.

No other source of water should be available. You need to treat every chicken on you place ASAP.