Pain during intercourse while on the pill

This happened to me years ago but I still wonder about it! I was on the pill (alesse) for about 2 and a half years and suddenly I started getting a burning sensation around the opening of my vagina during sex. At first it was only when he first entered me but over the course of a few months it got progressively worse and throughout my whole vagina to the point where it hurt the whole time and I was almost in tears. My doctor prescribed me a cream but it didn't help, then I decided to go off the pill after about 3 years in total. Within months the pain was completely gone. I'm curious if this has ever happened to any of you before and what caused it?!