last spring I got several khaki Campbells. Late summer I got a Muscovy drake from a lady and introduced him to the ducks. Until recently (3wks ago) he showed no real interest in them. Now he is mounting them repeatedly to the point that the back of one of the duck’s head started to swell. I’ve tried spraying it with an antiseptic (for poultry) but it has grown to the size of a golf ball. Any suggestions on how to treat IF it’s treatable?