My child's fingertips appear to be going to white, then going back to normal, then white again.?

Cold related color? Usually quick changes in skin color can be related to blood vessels. In this case, if blood vessels get small to conserve heat, color will turn more white. If they stay that way, you may see blue. When the vessels get bigger again, you may see flushing, or pink to red. Some people have more reactive vessels than others, and some can experience pain/tingling with this, such as with reynaud's.