I'm A Scuba Instructor. Today On A Teaching Dive I

I'm a scuba instructor. Today on a teaching dive I had a sharp pain across my face from my nose to my ear. When I got out of the water I had a pretty nasty nose bleed. It stopped fairly quickly. I didn't have a cold or anything that would cause me to worry before this dive and I dive a bunch. Wondering what I can take to avoid this happening.