Was it the same size as in the pic when first seen by the vets or has it got a lot bigger since?
Insist on a UV lamp exam and if that clears it for ringworm, then a skin scraping for mites.
Please let us know what the verdict is.
Edited to add: Hey, 5 weeks and they've never been outside? So never exposed to direct sunlight? Ask your vet about psoriasis. You need sunlight and diet change and some topical meds to clear up psoriasis in pups.
It was the same size but flat when first seen by vet, once it raised i went for a follow up.
They are 8 weeks now, but at 5+weeks when spot came they hadn't been outside, they did get sun light as i have a sunroom, where they bath in the sun, They have since been outside everyday and love it. They are fed on Advance puppy.
i will let you know what happens today at the vet.