Sinus Pain in Meditation

I’ve been meditating for about 5 years. At the beginning of my meditation sessions I experience a pain in my sinus area, similar to the pain experienced when water is breathed in through the nose by accident. This pain was more intense for the first few years of meditating but has become almost non-existent now, except for the occasions I have let things get in the way and have not meditated for a few days or so. Now the feeling is not so much a pain as just sort of an opening up or a flow of energy through that area. Do you have any insight/opinions on what this could be?