It looks like there's a bump under his skin? I don't know if it's the same thing but my pinstripe had a bump like that, although not as big from what I can see in the picture, and it went away after about two sheds. I don't know if it was one of his scales turned under or what but I just monitored it to make sure it didn't get worse and he didn't seem bothered by it even if I touched it. So, I waited a few sheds like someone suggested and it did go away. I'm not saying that yours is exactely like mine since it's hard to see in the pic.