Just went to close the door to the barn and we have 4 week old ducklings inside a closed in pen inside of the barn. One of ducklings suddenly ran around in crazy circles and flopped on its back, unable to ger up, I thought it was dead. I picked it up and had to hold its head up. After a few minutes she seemed to hold her head on her own and just sat on my lap. When I put her back down in the pen, she didnt want to walk and seemed to be unsteady. I thought maybe a seizure? This lasted a few minutes, then she walked around fine. I told my husband and he said she seemed unsteady last night, but was then fine after a few min. Any thoughts? The get duck starter feed with Niacin and we take them outside in the yard with us on warmer days.