Link Between Migraine and Sex

I have had migraines since I was 8 years old. Debilitating, blinding, vomit inducing, bed ridden migraines every month. These things were the most constant thing about me, I knew them like the back of my hand. Vision gets fuzzy, blind in left eye, completely blind, vision comes back, migraine hits, vomit, pass out, wake up, all better, and move along with my day! I am now 22 and in August I started having sex with my boyfriend. I HAVE NOT HAD A MIGRAINE SINCE. We were long distance so it's not frequent sex, only when we visit. Has any one heard of a link between migraine frequency and sex? I'm not complaining, but this is so strange to me.