I would buy a can of provent-a-mite from Matt (mgreptiles.com) Other mite sprays are pretty lame compared to provent-a-mite.. that stuff will kill ALL of them, and it keeps working so when any eggs hatch, those mites die too.

To help your snake feel better (at least temporarily) you can soak her so she's mostly submerged (not her head of course and supervise her) the water will drown the mites that are on her and make her feel a bit better. She should be able to shed ok.