Hi, I have a red-eared slider and I got him in May, he was a baby. Lately he has been turning white behind his head and his sides, on his shell. Like a discoloration, it is not flaking or soft. It looks almost like it is bleached. Please help!!

I could not post a picture because I have no url, but if you can help I can email one. My address is: Jessicaturtlepink@yahoo.com
Thanks!