sudden leg paralysis

I'm a newbie with ducks. I recently (about a month & half ago) purchased 4 at a farm store. 2 pekin & 2 Cayuga. Not to sure on sex.This illness has came on all of a sudden with 1 of the pekin. One morning(a few days ago) I let them out to the pen in the yard then later on that evening he/she...

She didn't really eat much all day but she's been drinking water my husband went to Walmart and bought her a mealworm sunflower treat bar which he ate as soon as I put it in their cage but when I came back from the bathroom she was lying on her stomach with her legs stretched out behind her...