My current problem is... I have a female silver call (looks like a female mallard but smaller) who has been having health issues. She has lost weight Not too interested in food; even most treats Biting at her lower belly (behind or between her legs but in front of her vent) She doesn't oil herself because shes obsessed with this biting She swims but keeps her butt up When she's out of water she holds her butt low She began hissing when I get within 2 feet to look at her (Recently) She flutters her wings as if content I've had her to the vet. There are no worms, no other "bugs" but the vet sent us home with antibiotic because of the "unknown" possibilities. She is really worrying me. We've had 2 close calls of loss but had lost other ducks due to causes that were unknown over the last 3 years. One female and 2 males. I am not a doctor/medical person but I love my ducks and I'm learning to do almost anything for them. She does nibble her food and likes worms (red). We live in Wisconsin, in the country. They have a man made pond that is sum pump fed (newer built house). It's enclosed, and was completed 7 years ago. Any ideas would be great.