My 1 year old son is acting strangely after having been sick.?

He's been biting various objects and then crying, cuddling closely to his mother at night when we sleep, throwing objects, and has stopped being as affectionate as usual (not giving kisses as he usually would in the morning and before sleeping). He won't lay down for his nap as usual, and he has been crying for seemingly no reason. We're quite sure he's stressed in some way, but don't know why or what to do to help him get over this. We have been playing with him, taking him out on walks to get out of the house, and trying to give him what he wants within reason, but it doesn't seem to change anything. He is quite an active baby, as he doesn't like to sit still unless he's playing. Please help!