We have several baby chicks that were hatched out in our coop by our hens. With that said, we just recently found out they must have some sort of mite or lice because when handling the chicks / chickens we have found tiny bugs on our hands or arms! A tiny thing, but it is a bug of some sort (mite or lice, but uncertain which). So, we just found the bugs yesterday. We are treating them today. We have lost at least 6 or 7 chicks in the past few days. Seem to be losing like 1 a day. They go from normal to sick fast. Does this sound like it's the mites or lice? Right now I have one, maybe two that don't look like they are doing very well. I tried to inspect, and I didn't see a mite or lice on it, but this chick is obviously going downhill rapidly.
Could it be something else? I have isolated that chick, and have a heat lamp on it. Anything else I can do? Should I rub the sick one with the seven dust (just purchased today) right now too?
Thank you for any and all help!

Thank you for any and all help!