Permethrin spray will work well on getting rid of mites. You may need to have someone help you spray the birds, but one of you can hold them as the other blows or pulls back the feathers and can spray near to the skin. Make sure to check really well around the back of the neck and around the vent. Bugs love to hide in these places and lay eggs.
Then clean out the entire coop. Nest boxes and all. Scrub around and under roost bars. Mites love to lay eggs under the bars and in cracks. Nest boxes too. Just clean everything down really well and spray with permethrin, Sevin and DE. Use it all if you can. Repeat a week later.
Same with the birds. Spray them down at least once a week. Keep up with all this for one month. You should be fine.