Humidity gauge shows normal moisture levels in my house, but my nose/sinuses feel painful /inflamed and "dried out." should i use humidifier or not?

Yes: Try it and see if you feel any better.

Define normal: The comfort level of humidity for most runs around 40-50% .Levels below 20% have a significant drying effect on the nasal passages & throat & can cause headaches & sore throats. Humidity above 50% allows dust mites to thrive in your home & above ~70% you can promote mold growth like in your shower. A simple digital humidity gauge in your bedroom can help you decide whether to run the humidifier.