What a cutie! Going to be a smarty pants.
That paper then is a concern - that seems like it should dissolve, but I have an otherwise smart GSD who will eat paper - for her, it does not go through easily. I have a mix who has eaten paper towels and passes it like it's nothing. I am not leaving this stuff out for them, and try very hard to prevent them from getting it, but sometimes they do, and when my GSD does, it's going to take a while to pass, and she's going to be uncomfortable - I am knocking wood that she has never eaten enough to cause more than that, and continue to up my level of monitoring her (gating her off when I leave the room, etc).
So while that may be part of your puppy's problem, I would continue to keep an eye on him, because it may only be part, or it may be it. Who knows, but I would not use rice as a mixer for any puppy. Everyone says to do it, but to me, not a good idea.