Ventral scale rot or Ulcerative dermatitis

Causes:

substrate kept to moist,
Unclean substrate resulting in bacteria or mould build up, This is sometimes said to be caused by under floor heating, which if the tank is not cleaned regularly could be true.

Symptoms:

Appetite Loss.
Red patches on the ventral scales, which if left untreated will develop into open sores.
Blisters on the ventral scales.
Mild cases can be treated by cleaning the wound each day with warm water, and then applying vetadine. While treating the animal keep in a bare tank on Kitchen roll, this should help eliminate possible infection. In server cases consult your vet.