Hi, I should add that to get a representative sample from a skin scraping it's best to have whoever is doing it to use a scalpel. I know it sounds risky but used properly you shouldn't end up with any cuts.
I only mention this because the first scraping I had done by a phelobotomist was performed using a plastic card. This only scraped superficial dead skin cells, with the test coming back negative. To get a sample with the mites requires scraping further down. So for the second time i had my Dr do it personally. Also stop using any creams or lotions you've been taking to treat the skin. This'll ensure you have a full blown population of the blighters if you have them at all, leading to a positive diagnosis and then a course of treatment. It's the unconfirmed diagnosis that leaves so many people in limbo. I know, I've been there.
Let me know how you get on.