[anonymous]

I wonder if you are feeding them too much? Could the food be high in fiber?

I never feed just kibble (too dry) add a little boiled chicken meat and rice (give up the rice when there stools have been firm for more than 3 days), add a little water or plain homemade (nothing added) chicken broth to meals.
Don’t free feed/leave food down.
Feed 3 small meals a day for now.
I have heard good things about Pro Plan Focus salmon for sensitive skin and stomachs
Make sure the food that you choose is appropriate for large breed puppies, it will say so on the bag.

PS: Wait a minute. You got them at 4 weeks? Not good for the immune system. Way too young, they should stay with the mother till at least 10 weeks.
Let me guess, they had a load of vaccinations recently.
Best to spread those out, don’t give all at once, and hold off on the rabies (required by law) for as long as you can, at least till they are 6 months old.