I've been finding that when I dive, after about half an hour underwater (regardless of depth - it's happened at max depth of 8-30m), I get this stabbing pain behind my eyes. It's a similar sort of pain I get at the onset of a migraine (the dive Dr was aware of my migraines from the medical questionnaire I had to fill out when I was getting my dive medical earlier this year - he didn't seem to think it was a problem). I've never had any sinus problems in the past. I regularly clear my mask when diving, so don't see how it could be the result of mask squeeze (?). The pain tends to disappear about 15 minutes or so after I get out of the water, but makes the end of some dives pretty uncomfortable. Does anybody have any ideas?