My adult box turtle developed rusty coloring around the edge of his shell. I soaked him in baby carrots and when I took him out I noticed very tiny pieces of shell floating in the carrot soak. He also has stopped eating. Is this shell rot? I have had him for years but just recently put him outside for a couple hours each day in his pen when the weather opened up, and brought him back in for the evening. The temperature was between 55-68. Any thoughts would be appreciated. Thank you, Kathy Mitchell