Dog skin diease? Can it be treated or not? On Bichon Frises.?

Have to be more specific than that, depends on what disease!
References :

the best thing to do is go to the vets…. acording to wikipedia

" Skin problems in Bichon Frisés were less often reported by owners in a 2004 UK Kennel Club survey, but were still more prevalent than among other breeds.[8] Other health issues unusually common in Bichon Frisés include Cushing's Syndrome, dental disease, patellar luxation and cruciate ligament tears, and bladder and kidney stones.[7]

Bichon Frisés, like many other dogs with fluffy, flappy ears are prone to ear mites and usually need constant care around the ears."

hope this helps
References :
wikipedia

Bichons areknown to suffer from skin diseases.
The first thing you should do is take your dog to the vet for a skin examination and scraping.
Various things can set off skin infections in this breed:
mites
wrong diets,High protien diets and additives in the diet
Strong breeding
dirty coats/flea infestations
Central heating

No matter what the cause it should be controlable
References :
Experienced with bichons with skin problems
experienced with bad diets in bichons(certified in pet nutrition) and advised on proper diets. Also taken advise from veterinary aquatances who have treated the breed

I have just fostered a bichon from were a work in rescue center. she is starting to show signs of skin problems she is constantly biting and scratching at herself and is now showing marks that resemble hot spots she is flea free but when she is biting herself she then starts chocking like she as swollowed some of her fur. I have trimmed her fur shorter to see if this will resove or lessen her fromdoing this she is a lovely little thing