BP's will sit in the water if the temps are too warm...and this is clearly not the case here (please seek correct temps). This means mites.

I would recommend a bathing procedure in warm water as outlined in the Barker's book...2-8 hours keeping the water at about 80 degrees (this will require a hot pad). Then rub the snake down with Reptile Relief to kill current mites and use Provent-a-Mite on the enclosure.

JonV