Swelling of eye

I've had an ongoing eye issue now for 9 years and have been to several doctors and still no answers. It started when I was pregnant with my son, then occurred about every two or three months just with my left eye, but for the last 5 years, it swells monthly and often one eye first and then a few days later the opposite eye. It swells alot during my sleep but then at all random times during the day. It starts in the corner of the eye and then progresses down and normally takes a good 48-72 hours for it to go down. It has happened after intercourse and seems to occur about a week or two after my menstrual cycle. I'm going crazy trying to figure out the cause. HELP!