he wont stop scratching

my dog diesel has started rubbing his back up against everything, hes now lost his fur off his tail and back and bleeds from rubbing, im at my wits end, he bites, scratches and rubs himself all day, even more so if im on the phone or have friends over, he dont stop except for when hes sleeping, hes started on his ears now too, iv tried everything, mite drops for his ears, creams for his back, sulpher block in his water, hes had flea treatment and been wormed, got no ticks, just cant understand it, i have two other staffs who are 5 yrs old and they are fine, any ideas please, iv just edited this post because i forgot to say hes never been well since i had him, when he was a pup he was back and fore the vets with diarrhoea, sickness, ear infections, the lot, i was rushed into hospital in april and diesel had to stay with a friend who took her eye off the ball and he had is wicked way with her staff, who had one pup, the pup was alive but died has soon has it was born, the pup was missing his front legs and the face was deformed, i had no papers with deisel and couldnt contact the breeder, hed moved within days of me having him,

Vets to be honest, a lot of the signs are mange, which isn't uncommen Xx

i would defo take him the vets my friend has staffy and she bites her back she has a mental block that makes her think she has flees all the time even when she has'ent no they are looking for a behavour specalest

rockys feet went red once and he had lumps under his chin, but it just disapeard he may be allergic to something .... anything all dogs are differant good luck with that one

I would definitely take him to the vet first of all. A skin scrape may be needed to determine if it's demodex or not.

In the meantime you might want to try these............

http://www.happystaffy.co.uk/itchy-skin-solutions.html

Someone I know with a Bull Terrier swears by them, especially the 'Itchin for Relief'.