This afternoon, I checked on my tortoise, and I noticed that there was an odd growth right next to his tail. It just appeared today, and may just be something that got stuck on the way out (is that possible?). I recently began feeding him a new food, and he seemed to be fine with it. He began sleeping in a different location two or three nights ago, if that's helpful. I don't have a picture, but I'll get one soon. What should I do?