What is the cause of headaches, congestion, earaches, headaches, and nausea?

Sinus infection: Headaches, congestion, earaches, headaches and nausea are often associated with a sinus infection. The inflammation and irritation may improve with the Nasonex (mometasone) and singular that i see that you are taking. What you are trying to do is to decrease the build up of the fluid in the sinuses that leads to the pain. If there is fever, then you need to be more concerned that the infection is increasing.