The red areas on your rooster combined with feather loss indicates some sort of irritant like mites or lice. If it is lice or mites, treating once will not work. It will take several repeat applications to both birds and coop before you eliminate the adult bugs and the bugs that hatch out of the...
You need to follow up spraying for mites and lice with repeat treatments every week for a few weeks to make sure you get them all. They may not look normal again until after they molt.