When my waters broke at 39+6w the midwives kept a close eye on me (had thrush more than 5 times over the 9 months and was only just getting over it AGAIN), and wanted to make sure I didn't get thrush. They wanted to treat it quicksmart... so I don't know who told you not to treat it...? I would go talk to a pharmacist and get their advice on it. Also talk about your DH too, he may have a silent form.