loss of coat in round sections and scratches like mad making himself bleed other dogs never affected suddenly it dries up and goes looks horrible when he has it

Ringworm?? Which is a bacterial infection of the skin and not a worm parasite...
Would need a vet's visit to confirm etc.

If they arte round hot inflamed sores that ooze and then the fur drips out then they coudl be hot spots/wet excema.  this is also an angry bacterial/fungal infection.

If it is the latter then a duluted solution of Hibiscrub applied with cotton wool aqnd then rinsed off will treat the bacteria/fungus and it should subside. 

If it is bad and the dog won't leave it alone aafter you ahve started bathing it an antibacterial cream like Fuciderm from the Vet will clear it withing a couple of days. 

The skin will return to a healthy state and the fur will start regrowing within a week, tyhough the dog wil look moth eaten as it will be darker than surrounding area.