J.B.
Instead of just changing toothbrushes every month, are you changing them 3 days after the initial diagnosis and then 3 days after starting the round of antibiotics and AGAIN at the end of the antibiotics? That's what my doctor and my son's doctor both told us to do (also Lysol wipe the openings to toothpaste tubes). My oldest and I both had it at the beginning of December and again at the end/beginning of January. There seems to be a particularly nasty strain going around! I had Lysoled, washed, changed toothbrushes (once -after the sickness) and all of that, but evidently the toothbrush thing is a big deal as well as anything else that may possibly go in their mouths. Hope this is the end of it for you! It's been terrible this season!