Multiple times before visitation, my son’s mother has said that Charlie’s sick. It wasn’t a “be forewarned, he’s sick. He’ll need XYZ medicine, etc.” Rather, it was a simple, “He’s sick.” End of story.
At the time I just thought whatever, she’s just letting me know he’s not feeling well. Oh well, we’ll get through it.
Only later after lots of research on the topic of brainwashing of children did I realize that this is a commonly used tactic by ex’s who don’t want your son or daughter around you.
Your only solution is to do what I did, tell them thanks for the update, and reconfirm the pickup time. If your ex suggests no visitation because of the illness, politely inform them that you will take care of the child (and are open to medical solution suggestions), and that to deny visitation would raise the matter to a new level.
Sidebar: Keep in mind you’ll have to judge the entire situation: If the child is indeed quite sick, would you want them to be around your healthy house? A good technique is to speak to your child and gauge the extent of their illness over the phone.