puppy bald patches

can anyone help,i have a litter of 9 blue staff pups and 2 of them have small round bald patches on their heads,abdomen and tails.they have been to the vets who checked for mange with a skin scrape which came back negative,so she gave us an antibacterial wash for them to be wiped down with daily.it was no better so i went back to the vets to get the results of a ringworm test which was also negative,she gave them both some antibiotics which they have been having all week but they are still no better.does anyone have any idea what this might be it started at 2 weeks of age non of the other pups have it and mother and father of pups are fit and healthy.the vet said that it wasnt a flea allergy even though they wasnt tested,i also asked if it could be food allergy and she laughed,im at my wits end as noone seems to know what it is .they was given another skin scrape a week later but was also clear of mange .these patches of hair loss are tiny some of them had a small raised pimple before any hair loss and the pups havnt been itching at all any help would be great thx

Could i just ask if both the parents are blue as well? Im no expert but im sure i read somewhere on this site that breeding 2 dogs the same colour, i.e 2 blue parents can lead to the pups getting alopecia. Im sure here is a thread on here somewhere.

Like i said i'm no expert. in fact iv'e only just got my first staffy pup

Blue staffs are prone to skin conditions so i have heard if the vet can't suggest anything concrete research the condition yourself. Or go to the library for a book. Pointless giving them
Medication they might not need id also try another vet .

Also wondering about CDA (colour dilution alopecia)