I bought a few ducks and two seemed to have this problem as well. They did come out of it. My guess was they were dehydrated. When they actually drank water ..alot of it ..this scooting happend...and if I scared them by trying to catch them they actually try to stand and run which made them walk drunklike or fall over and stiffen up. They did this like first 2 days. But all turned out well. Possibly similar to your situation.