Terrible breath!

All of a sudden this week our little guy has got the worst smelling breath. It's the worst in the morning, and seems to get better throughout the day. We wipe out/brush his mouth every day in the bath (just water). I looked for any solids that might have gotten stuck in his cheeks. We have a doctor's appointment for tomorrow for congestion and cough (and maybe an ear infection).

Anyway, does anyone have any suggestions to help this little stinker? Thanks!