You may be over crowding them. Quail go off on each other when cramped or over heated. Make sure your ratio is correct for Coturnix...1 male to 4 to 7 females. Give them at least 1 square foot per bird, more if you can afford it. Feed them gamebird food of 24% to 28% so they are getting enough protein. And if you have an aggressive bird in the group, you may need to separate them out permanently.
And yes, stop by our quail section for more help with this. Enjoy your quail and welcome to our flock!