Hi anyone who can help me! The past two days I've noticed one of my pekin ducks seems sick. Even my husband noticed and he doesn't pay much attention to them. The duck is way slower than the other 3, closes it's eyes a lot, lethargic, and looks thin compared to the others. It's living quarters is inside a coop at night and free range during the day with access to a small pond (since it's in the sun algae does grow quickly, I once a week bucket the water out and clean the tarp and replace with fresh water). They eat an all flock crumble food and They are about 3 mo old. Can anyone help me?!?