get rid of the heat rock. they're really for lizards.

i think your BP is hiding under the heat rock b/c it feels insecure in the enclosure. u need a closed hide, one on the hot side and the other on the cool side. place the hot side hide over the under tank heater. also block on the back and sides of your tank with paper.

lastly get your under tank heater (and hot rock if u insist on keeping it) on thermostats. unregulated heat sources will burn your BP and aggravate it's shed.