My down Clown

[Goat]

My Clown fish looks like she might be sick ,, he hovers near the sand at the bottom of the tank , she is no where near energetic as the little clown that is in there with her,, it doesn't look like she eats ? Every one else in the tank eats so well when I feed them mysis shrimp ,,, my other clown goes everywhere in the tank while she hovers at the bottom ,,,, it also looks like there is something white on her upper back near her fin on the right side of her