They sound like they could be mites, make sure you put the under the tank heater on the side of the enclosure , I think somewhere I saw pill bugs help eat the mite eggs so you could try that, Ive never had a large infestation but at one time I did have an emp with mites it was only a few and put him in very shallow water and once they came off pulled him out, obviously you dont want to have you're little guy drown though.