Clown fish

Hi i have just bought 2 oselaris clowns 1 black and white and one orange and white.ive only had them for 5 days but over the last couple of days they seem to be at the bottom of the tank on one side.the orange one is a bit bigger than the black one roughly an inch long the black one keeps rubbing against each other and the orange one just seems to paddle about a little some times going vertices then back down almost laying on its side and the black one constantly rubs on the other and looks like he's nudging .the black one is eating the orange one has had only a little.and dosent move much to get the food not showing much interest.why are they doing this.