It's a hard one. The policy at the school where I work is to use common sense. I would not normally allow a child of that age a loo break, as, has been said, it is a contagious condition, and there are breaks when they can go. Having said that, if I see a child is truly distressed, I let them go, but only one child out of the room at a time.
Do you still wear you original wedding and engagement ring