Post nasal drip can cause some stinky breath and congestion could be why your little one is breathing through their mouth. Maybe see about an allergist referral?
I wish he liked brushing better he used to do so well with it but now he barely lets me get at them I hope it’s just a phase. I haven’t noticed bad breath but I’ll sniff tomorrow
We are in the same boat ! My daughter is definitely a mouth breather when she sleeps . I started noticing the stinky breath when she was congested . Our dentist recommended we brush and floss twice a day . Lately she hasn’t been fond of getting her teeth brush