What Do White Spots On The Lower Gum Indicate?

My 8yr. Old daughter has been having small white blotchy spots on her lower gums behind her lower lip that come and go every couple of month. The blotches look kind of cottony. This has been happening about a year. She got her first period last month. I thought it made might be related, like a changing over thing. One time there were two painful very small bumps the size of flea bites on the underside of her lower lip that were ether white or skin color, it was hard to tell. But we re got a short time later. And the next day a bearly visible blotch was right next to the skin thing that s connected to the underside of the toungh. I took my daughter to bthe walk in clinic a few times but by the time the doc looks at it the spot or spots are not there anymore cause they come and go so fast and I end up feeling like a dumb ass. Plus transportation is not easy for me. Can anyone help me?