Kitten and litterbox help

Hey guys, I'd appreciate any help or advice regarding one of mi kittens. I have 2 around 6-7 months old a grey one and a black one. The black one since yesterday keeps going back to the litterbox and digs out poops and keeps playing with them, he keeps digging until he finds one and then he just starts going ham everywhere with it, when I take it away he tries to go back for another one, they have plenty of toys which sometimes go under the couch, I'd just take them out and give it back to them, litter brand is the same I use always, its changed regularly and I scoop daily or each time I see a poop in it. But ever since yesterday the black one just went coo coo. Any help is appreciated.