Hi, I am Dr. Peter and would like to help.
1- How long has this been going on?
2- What food is he on now?
3- What was his old food?
It has been going on about 3 months
He is on IAMS Lamb
He was on Science Diet sensitive stomach
1- Can you rub the tips of his ears against each other for 20 seconds and see if this will make his back legs move has if he wanted to scratch?
2- Is he licking his paws?
3- Did he get better on the cortisone?
Nothing with the ears
no chewing or biting (licking paws)
cortizone helped some but not fully, and when it wore of it was much worse.
It seems he may be having allergies. Dogs when allergic to environmental or food they develop itch in the skin. The darkening of the skin is the result of chronic inflammation, probably as a result to allergies. I would recommend you put him on a low allergen food like hill's z/d for at least 6 weeks. During that period he should not eat anything else or the trial will not work. In addition, speak to your veterinarian about putting him on Temaril-P which is a combination of an antihistamine and a low dose of cortisone. This will make him feel better until you completely wean into the z/d.
If you have additional questions I will be glad to answer them.