Might be the bone then. Hard to say for sure without an x-ray. I would just keep an eye on it for now and make sure it doesn't appear to get larger or spread. In the meantime, fine tuning the UVB output is a good idea.
update, i have came home..the area of the tail has become very pale like alot brighter then rest of tail, the tail itself is already blurry because im expecting a shed soon, but this i mean its really bright
Yeah it's a good possibility. When they shed, sometimes their skin will swell up (this is quite noticeable on arms/legs and toes/fingers) to help loosen the skin. It goes back down to normal once the shed is done so keep an eye out for it returning to normal when the skin comes off (which may take time and not be all at once).
Not necessarily. They often shed in patches and there isn't necessarily and rhythm to it. Sometimes they'll shed just a single finger or even a single scale. Sometimes half of their face will shed. My guy just shed one finger the other day and has been working on an ear shed for almost a month now. It's just how they are and not cause for concern.