I have heard of that "Fifth Disease". One of my sons had it when he was younger.

When you're a mother with a sick child, you could give a rat's ***** whether is techically the same or different.

Your child is hurting. You want to know what you can do to make him feel better and ease his discomfort. Because his pain is your pain.

(Frog steps down from soap box)

Instead of flapping my jaw, I wish I could offer some great advice. How about...
Give your daughter & grandson a big hug. I don't know if it will help them but it will sure make you feel better.