Thanks for the answer.
He certainly doesn't seem to be doing very well with Zyrtec so I'll switch to diphenhydramine tomorrow, as you suggest. I'll also get the topical anti-biotic and soap.
His diet has not changed at all so curious as to how this could be a food allergy? Can they have reactions to stuff that they've tolerated in the past?
The only new thing in his diet is a new pack of raw hide dog chews that I've recently bought which come in array of colours - he's had them before but I've heard horror stories on dog chews/treats before.
Also, what are your thoughts on this possibly being mosquito related.
Also note : his lower abdomen (near his privates) is very hot as are the insides of his ears. He also tends to lick his penis a lot and that too looks red and inflamed.
He never cries or moans but this is really getting on top of him and he's starting to whinge, so hope we can help out.
Thanks for taking time to elaborate a little bit more.
Ok, thanks - last follow-up question - I don't like the idea of a collar to stop him scratching. If I couldn't at least satisfy/minimise and incessant itch I'd go mad. Could I perhaps put sock on his paws instead, as they seem to be getting it worst?