(I've learned my lesson on this one) they must be dewormed at 2,4,6,8 weeks....
Also, 5 week old pups still have to nurse
from their mom. So, I guess the pups' feces will just have to be cleaned the soonest possible so the mother wont eat it.
As long as they are still eating and drinking then they'll be just fine.
I've read that pups can get diarrhea from a lot of reasons, sometimes they can be treated at home if the cause is not bacterial, or parasitic or from eating toxic things.