What Causes Onset Of Menstruation And Abdominal Bloating Post Intercourse?

Hi, I am 49 years old, I thought I was in menopause because I did not have a period for about 8 months. Then I had intercourse I night in September 2014. a few days later I had what looked like a light period. then I had a heavier period 2 weeks later. now I am very bloated and my stomach appears to be growing.