I would call the vet though. Little pups can dehydrate quickly. With a round of the runs she may have the sensation to poo even though she is empty but it sounds like she has picked up something (virus/bacteria).
NAPWDA Certified Cadaver Dog
Waiting at the Bridge (italics
=GSDs) (hemangiosarcoma=blue):Grim , Cyra, Toby
, Rainbow, Linus, Oscar
, Arlo & Waggles