Yes, lice are gross! When treating for coccidiosis I have seen others recommend treating again some weeks later, I have never done that. If everyone bounces back quickly I just do the one week, if they are slow to recover I do the second week at the lower dose. Any that are not drinking well I would continue to give them orally until they are since the meds can't work if they don't take them in. Corid is pretty darn safe and overdosing is not really a worry. Once birds recover they will have some resistance to whatever strain(s) of coccidia they have been exposed to and should not get sick again unless exposed to a new strain or if they have a compromised immune system from something else. Some strains are more virulent than others and more damage more quickly, so starting treatment as soon as symptoms appear can prevent more severe damage. There are some strains that have become resistant to amprolium (corid), I've never dealt with one. Since your birds have improved some I would think it's working. For strains that don't respond to amprolium then either a sulfa med. (sulfadimethoxine, brand name Albon) or toltrazuril (Baycox) are often used. Amprolium (Corid) is the most common treatment and the easiest to get.
You can give probiotics any time, including during treatment as long as they are just probiotics and don't contain vitamins. The vitamins should be done once treatment is complete.
You can give probiotics any time, including during treatment as long as they are just probiotics and don't contain vitamins. The vitamins should be done once treatment is complete.