Is he nipping for attention? Also he is neutered and could still be moody, its takes time to settle, my Olly is neutered and very territorial about his cage, he will stop soon I know, he was only neutered in March, no need to panic I think your bunny needs time like mine, Olly hasn’t bitten me but does not mean he won’t, have you tried giving your bunny some greens or fruit to hand feed him to let him get to know you? Some rabbits bite for attention which they learned from the last owner, its like with a toddler he does wrong you give him a treat, he does it again you treat them, if it is that do you have a pair of thick old gloves so if he bites he won’t hurt you and learn that being naughty gets him nowhere? Also if you are picking something up off the floor is it something of his? Like a piece of cardboard or newspaper he was playing with and claimed as his? Because territorial bunnies do this, its like. “Hey that’s mine!” I’m sure he will calm down soon.