Nursing dog has terrible diarrhea?

4 weeks ago she gave birth, this was not a planned pregnancy and she had a check up when the vet told us it was just a phantom pregnancy. She would have been almost 7 weeks pregnant when she had the check up! Anyway we have 7 puppies and they have all been vet checked at 3 days old, 2 weeks and are back on thursday for worming as is the mum. She has been on antibiotics twice in this 4 weeks for diarrhea each time ive taken a stool sample and its come back clear, she isnt cleaning up after the puppies anymore, and shes being fed on wainwrights salmon and potato puppy food, ( shes alregic to rice so very little else she can have ). My vet has said it's normal when nursing but i think it's getting to much now, she's really starting to look thin. She has been wormed at the same time as puppies aswel with panacur. Tinned pumpkin doesnt work with her either. She's had blood tests last week and she's fit and healthy, am i worrying over nothing? I know how ill i feel when i have the runs, i dread too think how shes feeling with nursing 7 pups too. Oh and shes a husky but they have dodgy tummys anyway, her poo was fine before she had them.