Found earlier on my new.beardie i keep the cage clean and it has proper heating and lighting. The beardie is only around 4 months old got at pet smart on June 4th never noticed and yellow here when i first got it or anytime until recently this is the only area that is yellow and it is like there is a bump in the middle of the yellow that is sensitive. Pics included in link. https://imgur.com/a/g0QqMp9