My male mallard duck has been fine with our small flock of 5 chickens and our one female mallard duck for about 2 years, but recently he has been being aggressive with our chickens. We seperated the run with a gate, but one chicken managed to get over, and when we went out to feed the birds, her butt was swollen and red and bloody and she was covered in blood. For now we locked the chickens in the coop and kept the ducks in the run (one male mallard duck and one female mallard duck) i dont know what to do and i need help… are there any antibiotics that i can give the injured chicken??