Mites are one of the hardest things to get rid of. It can be overwhelming. But just keep at it. What type of floor and bedding do you have? Can you see any evidence of other mites on the roosts, walls, or floor. If you are still dealing with them, I would do a complete coop cleanout. Do you know...
There are a lot of threads and links to read about depluming mites which can lead to feather loss, itching, and cannibalism. Have you had a vet confirm them, to differentiate between other mites? A microscope and skin scraping might be good. Ivermectin pour on seems to be the main treatment. If...