this is interesting to read

"Certain mites migrate from birds, rodents, food materials, vegetable matter and house dust, either attacking or annoying humans. Some mites can be detected with a hand lens, while others require microscopic examination of skin scraping or even dust from vacuum cleaner bags. Mite irritations can be confused with entomophobia (fear of insects) in certain people. Mite diagnosis is often difficult because specimens must be collected and identified by trained specialists before treatment can be made."



Tropical Rat Mite
This mite will feed on humans even when rats are present, causing painful bites, intense itching and dermatitis. Barely visible, they are bright red to black with white markings and are usually noticed on walls in basements, kitchens, bathrooms and where rats are found. Mites drop from their host after each blood meal and can survive several days without feeding

http://www.uq.edu.au/entomology/mite/ratmite.html

I don't know all there is to know about this mite, I am just posting this because what I read here sounds like a possibility.