I'm starting to think I might have a mite problem with my chicks. I've noticed one of my 8 week olds has a bald on a spot on his lower back. I'm assuming he is pulling out his feathers. I've heard that Ivermectin doesn't work the best as it used to. What would you recommend? I also want to treat my older birds as well. They haven't been around them but I want to treat everyone and get it under control.