These marks just appeared on my daughter, within the hour, the ones on her arm are now completely…

These marks just appeared on my daughter, within the hour, the ones on her arm are now completely gone, and more have appeared and disappeared all over her arms an legs and butt only. No fever nothing at all out of the ordinary even her behavior is perfectly normal but these marks are not, they are hot to the touch, raised like welps an extremely red, she does not scratch at them or notice them even, an when they disappear its like nothing was ever there.