I didn't know much about crested ducks before I had gone and got 2 of them.. I have since learned of thier physical and mental issues. One with a fairly large crest has been having seizures off and on for a while but now they are becoming frequent. It seems that it happens most when it is taking a drink or cleaning its feathers, it shakes its head violently and backs up real quick often falling on its side. Sometimes it arches its head back trembling and kinda flops around and cries loudly. Its the saddest scariest thing I've seen. I'll gently scoop it up and set it on my lap trying to calm it down. That seems to work sometimes but is there anything else I can do for it? S/he is almost 6 weeks old now. I apologize for the run on sentences.