My shih tzu has been panting and scratching all day could there be a problem she had pups 6 weeks ago

Scratching? As in itching? Where ? Are her puppies still with her (they should be) and nursing well.

Panting can be anxiety, heat, dehydration or fever. Please make sure she has plenty to drink.

If you have removed the pups already she may well need to see a vet ASAP to make sure she does not have mastitis or some other infection.

-beth

I too am concerned about the lack of mention of puppies. Removing puppies from their litter and mother iis a good way to create messed up dogs. Your question suggests you have gone ahead with breeding without educating yourself as responcible breeding requires.