Just recently, he has had really flakey skin on his back.
Is there something specific that can cause this?

We have 2 balls, a baby (jeffery) and our 3 year old (monty). They live together very nicely, in a 55 (i think) gallon tank.
We were using aspen bedding until very recently, when a friend recommended newspaper.
We use a zoomed heating pad for their heated side, which is usually kept around 85-90 degrees...the cooler side is usually between 70-80 degrees.

Any info would be very much appreciated...we love them and would be sad if anything happened to them!
thanks!