Just throwing out another thought.. Do you keep rodents? I remember having a problem with rodent mites a long while back and when I first saw one it was on one of my snakes I assumed I had a snake mite problem. I treated all the tubs in our snake rack and pulled every snake out to check for any creepy crawlies. Later, however, I found that the problem originated from a group of mice I was keeping. Apparently one of the newer additions to our mouse colony brought some "friends" with her and they multiplied and were in my snake room... Once we knew what was going on, it was just a matter of treating the rodent cages and the carpet in the room. It makes me itchy just thinking about it. Whatever it is, I hope you get it taken care of soon.