Thinking it might be air sac mites, I started them on the Iverlux, which has worked well for me before, when I first acquired my finches last year. At the same time I started them on Amoxitex, just in case it was some sort of respiratory infection. Tonight I got home and they seemed maybe a tad worse than yesterday. I have been administering the Iverlux to the neck, so I've been having to catch them every day for treatment. The Amoxitex has been in their tube waterer, and I removed all other sources of water from their flight. Tonight I gave the Amoxitex directly with a crop tube. This is Day 3 of treatment.
This is what they are both acting like. As I type this, the male is eating from the millet spray, and he seems a tad better than the hen.

What else could I be doing for them? I don't have any other meds at the moment.
All their poops look normal, there are no wet vents. I think they are undergoing some molting, and in fact the feathers on the male's head look a bit thin, to where I think it looks like thinning so you can see the scalp underneath. They share this flight with a male red-throated parrot finch, and he seems fine.
Any ideas what could be going on? I change their water twice a day or more. They haven't come in contact with anything new. I'm just clueless why they would be getting ill.