We have 6, 5 day old ducklings and just yesterday noticed one of them that couldnt swim as well as the rest and was fine when went in tbe tub....when we noticed he or she almost sinking we took the duck out and one foot turned in wards then we held her then the other food turned in wards n she couldnt stand very well so we took her back out n waited till she driednoff n put her back in when she started moving more.she is the smallest of them all then one foot went normal then both went normal then one foot turned inwards again n still is..what do u think it is?