Sores at the bridge of the nose or below the nose are usually due to tightening the headgear straps too much. The pressure will create soreness, then a bruise, and may eventually create an open sore if left untreated.
Headgear is usually tightened too much to reduce or eliminate air leaks. A small degree of this may be necessary, but too much is an indication that the mask is too large, too old or just the wrong style.
If your mask is six to nine months old and the silicone is becoming too soft to hold a seal, try replacing it. Find the right replacement cushion for your mask using our Mask Parts page.
It is usually necessary to stop wearing a mask to allow these sores to heal. A Nasal Pillow mask is also an option in the meantime.