YMMV - Your Mileage May Vary
With any luck, you'll know what the fussin' sounds like for each of the possibilities and the appropriate action to take.
As for teething, we also found some small mesh bags that look something like a pacifier. You put an ice cube (if you have one in a bug out) or even cold or frozen fruit inside and let the little one chew away. We got the best results when we pre-wet the mesh before handing it over. Keep a burp cloth or towel handy, though.
Others are available, but here's an
example of ones we've liked. For what that's worth.
My mom used to give me a teaspoon of brandy with a butterscotch hard candy melted into it. Sort of explains a lot.
-phil