So I have a 6 month old male bearded dragon and his tail is two shades(one darker then the other) and right where the color changes there is a bump in his tail .you can't see it but I can sure feel it.I don't think its tail rot because the underside of his tail is white

so i have a 6 month old male bearded dragon and his tail is two shades(one darker then the other) and right where the color changes there is a bump in his tail .you can't see it but i can sure feel it.i don't think its tail rot because the underside of his tail is whiteI was wondering if its any thing bad or is it normal