That is very correct, depending on the ammount of time you had it misdiagnosed will determine the ammount of time it takes your skin to heal and it could prevent certain treatments to work as the skin is to thick for the creams to penetrate, usually in a case like this you are pretty close to norwegian scabies. I would advice taking alot of hot baths for a couple months then try treatment again, loofa your skin and use exfoliating bars of vegetable soaps. This will help bring your layers of skin down.