Im new to the forums so HI!

I joined the forums because i need help with my finches.
I currently have 9 zebra finches. 4 pairs and a lone male. Each pair has a 4ft long flight (lone male has 4ft flight to himself).
The lone male is perfectly healthy and one of the hens paired up with a male doesnt appear to have anything wrong either.
(All birds are about 1-2 years old).
The other 7 though are clicking. No other sign of sickness or ill health. No runny poops. Cages are clean and tidy. Washed down weekly with soapy water.
One hen is clicking so much she is drooping her wings and sometimes open beak.
I have treated with scatt. One application and then 2 weeks later another application and im thinking maby again in a couple days so they would have been treated for the 6 week cycle of the mite.
BUT they are STILL clicking! The one hen is the worst out the lot!
I have no idea how to fix it!
Help!