oh gosh! that might be your problem right there! coturnix quails shouldnt be on medicated feed dear. They should be on nomedicated feed. Does your feed store sell any nonmedicated feed?
I was looking up some info on another illness out of curiosity and thought i'd look up info for you too......
"Avian Encephalomyelitis
Synonyms: epidemic tremor, AE
Species affected: The disease is most prevalent in chickens less than 6 weeks of age. Pheasants, corturnix quail, and turkeys...