Itchy french mastiff puppy

[Dr Meat]

Hello,I have got a very itchy 7 month french mastiff cross puppy.He has got small red raised spots that seem to move around, at first I thought they was flea bits so off to the vets! We have had the house fumigated, he has aways been teated with advacote and we have never seen a flea! so that rules out fleas. We have had a skin scrape test and that come back clear.He was given anti-histermins which have been useless. Hes always been fed on arden grange large bread puppy food witch is hypo-allergenic but I changed that to wainwrights so I dont think it is a food allergy. The vets have now given a steriod injection and therios palt 750 mg tablets. I have also tried flea shampoos and tea tree oil.
Any advice would be greatly received as its so upsetting watching try to tear himself apart!

[Dr Meat]

The cat does catch mice and feed them to him,I intercept when I can but he will swallow them alive if he thinks you are going to take them away! On the up side he won best puppy at a dog show today.

[Dr Meat]

Thanks for the replies,he it still itchy but I have been trying the sudacrem and It seems to be working thankyou all again.