Same thing happened to me .I wish I had taken pictures but was concerned about erradicating them and forgot. Mites are nasty small black or beige dots about the size of a period at the end of a sentence. I found them in the heat pits of my snake and around the eyes , in the chin wrincle, in between the belly scales and in between the cloaka scales. You can't mistake them for nothing else ! I too adopted a snake from craigs list and found out it was infested with mytes.
I bought some Reptile relief from Petco and it worked great killing them right away. However u probably got a whole bunch of eggs around the enclosure you gonna need to get yourself a can of Reptile Relief since it has a long residual effect meaning it will kill the larvae over a 30 day period as they hatch . Got mine right from the manufacturer no middle man and higher price.Here is the link http://www.pro-products.com/ Follow the instructions and you'll be fine ! Good luck