Staffordshire Bull Terriers

I HAVE A 6 YR OLD STAFFORD SHAR TERRIER AND FOR THE PAST MONTH SHE HAS BEEN SCRATCHING AT HER EAR SHE HAS SINCE LOST ALL THE HAIR ON ONE EAR SHE THEN STARTED TO GET CRUSTY EYES AND NOW SHE HAS STARTED TO CHEW HER BEHIND I HAVE TRIED THE BORAX AND PERIOXIDE MIXTURE AND THAT DOES NOT SEEM TO BE DOING ANYTHING ARE THERE ANY SUGGESTIONS ON WHAT I CAN DO TO HELP HER

What type of food are you feeding her, and have you switched her lately? I would take her into the vet for a couple of tests, yeast, and parasites (skin scraping). Has she ever had this before?
Have you managed to clean her ear out, or will she let you?
The best method I know is to put some warmed mineral oil in the ear, and quickly close the ear flap, so she can't shake it out. You then massage the whole ear, especially the base, where any junk might be lurking. When you've got that loosened (if there is any) you very gently use a long q-tip, and with out probing too far, see if you can get anything black or dark brownish red on the q-tip. If she has an ear condition, that exudate may also have an unpleasant odor to it. As far as her biting at her butt, have you had her anal glands expressed lately, and is she up to date with her worming? Good luck, I would take her to the vet as soon as you can, because you don't want her to suffer needlessly.