I have had something simelar happen to me. I went on a trip and then we got back and then two of them couldnt fly. I put them together in a seperate cage and then after about 1 week i got tired of having them seperated so i put them back in and after about 2 more weeks they recovered. One of their wings never went back, it still droops but it can fly just fine. Then 6 months later, another cock bird couldnt get up to the perches and it was just like it was not able to get to the perches. Then 2 days later it died. Im still not sure what that was but thankfully it hasnt returned.