Two days ago my DH rescued 2 abandoned baby mallards (mom and the other babies didn't make it). They were probably a day old. They were both doing fine then yesterday I noticed that the littlest one wasn't pooping normally. She would do that back-up squatting thing two or thre times in a row but nothing but a little liquid was coming out. She was still running around though. Now this morning, all she's doing is lying around and sleeping. Still no pooping. She was eating like a champ the last two days but today not a nibble. Day one I was feeding them smashed layer feed (same stuff I feed my grown ducks - all I had at the time). Then we picked up unmedicated starter feed and put them on that. Their pen is made of grass and hay - no newspaper or wood chips, a heat lamp and a water dispenser. Any ideas what could be wrong and how to treat her?