Sick Zebra Finch

Question
I have two male Zebra Finches.  I have had them about 3 months.  One of them is sitting on the perch with his head tucked to the back of his body.  He will sometimes eat, and drink when the other Finch chirps at him.  He will chirps back and eat and drink a little.  Please help save my butter!!!  <3

Answer
Well, the most common affliction of finches is sac mites. The best way is to hold the bird up to your ear and listen for clicking. If he clicks while he breathes, he has sac mites. This is easily remedied, the website provided sells a product called "Scatt". Just follow it's instructions and your Butter will be as good as new.
He doesn't click, please contact me again with a picture if possible and I will do what I can to tell when it is making your little guy sick