Sulfadimethoxine And amprolium for coccidia

[Cedarhillhomestead]

Hello, I have a group of 6 and 8 week old seramas. Any 20 total.
1 of the oldest and 1 of the youngest are showing signs of cocci. They’ve been outside for 10 days. The two are fluffed up and isolating. Everyone else is fine.
Here’s something I can’t find info on which is surprising: they have been on medicated feed which contains amprolium. Does that mean they have a resistance to it? I have both amprolium and Sulfadimethoxine. Just trying to decide which to use and if I can rotate between both to cover all the bases.

I did the 2 ts per gallon treatment as of yesterday and 1ml drench for both last night. Not a ton of progress this morning. No bloody poop but slightly runny. Thank you.

Pic for attention I don’t have one of the sick chicks

 

[Wyorp Rock]

Photos of the 2 that are sick and of their poop?

What do you mean resistance? To what? If they eat medicated feed with amprolium, do they build resistance to amprolium? It's not an antibiotic and afik, they do not build resistance. Amprolium is a synthetic B1 inhibitor that reduces the intake to the Coccidia oocysts and helps reduce their numbers by starving them out.
The amount of Amprolium in chick starter in the US is minute.

If they don't improve with the Corid in a day or so, or if they are declining rapidly, then use the Sulfa drug.

You aren't giving them extra vitamins while giving the Corid are you?

 

[Cedarhillhomestead]

Yes I’ve heard both coccidia and chickens can build resistance to it. Is that not the case? Poop looks normal I’ll grab pic today. No extra vitamins but I could not find any chick feed that didn’t have atleast a couple things added. Thank you!

 

[Wyorp Rock]

Yes I’ve heard both coccidia and chickens can build resistance to it. Is that not the case? Poop looks normal I’ll grab pic today. No extra vitamins but I could not find any chick feed that didn’t have atleast a couple things added. Thank you!

Vitamins/minerals in their daily chick feed is fine, they need them.
I'm talking about "extras" like if you give direct doses of vitamins/supplements.