What is this on my kitten

I took him to the vets for his first vaccination. I showed the vet his patches and was given Isaderm to use for 10 days I used it on him but he’s still scratching at his face which has caused it to a little wound on the face he is 3 months old . He’s also has a patch at the side of the face and on his leg. The person I got him from used to allow him to play outside in the garden I don’t know if that’s got anything to do with it . May I add the vet ruled out mange

Hello - I wonder whether this could be fungal in origin, for example an atypical Ringworm case.  This is definitely worth revisiting your vet about.  Until Ringworm can be ruled out, avoid contact between the patient and anyone who may be immuno-compromised.   It could also be possible that the anal glands are overfull and that this is a pain response, or that fleas could be involved.