shell falling off??

by LUCY
(UK)

I have a 7 year old leopard tortoise, i noticed that the bottom right (his left) section of his near his leg was peeling. There was no blood or any discolour. Now its fallen off and its hard smooth and yellow (shell yellow) underneath. look like normal shell except for the texture as it is now a smooth section. It now looks like the other side is mirroring this! whats up with him??