I got my Russian tortoise about three months ago. His shell didn't look too great then, but I'm noticing that the 'flaking' isn't getting better. Could this be shell rot, or shedding from growth? I got him from a pet store where they said he had been for about a year. They had no idea on origin or age of my guy. He has grown since I've got him, eats well, stays active. He's soaked about 2-3 times per week.