Forehead swelling

I've been having some problems with visible swelling of my forehead since I've been using my Swift (about 2 weeks). The swelling is in an area 1 inch high by 2 inches wide, directly above the bridge of my nose and feels squishy when you touch it. The swelling seems to get worse when I sleep longer than 8 hours, then gradually goes down if I get less sleep on the following nights. The swelling never seems to totally go away. When the swelling is bad, I also get sinus headaches (Sudafed normally helps with the headaches). Interestingly, I am having no nasal discharge, which is somewhat unusual for me.

I have a Remstar Auto (set at straight CPAP, pressure 10) with heated humidifier and a heated hose. I keep the humidifier on its highest setting. When I have tried the humidifier at a lower setting, the results were even more painful. I'm not sure if this is air trapped in my sinuses, or a sign of some other problem.