June 2015 I Got A Flat White Painless Lesion On

June 2015 I got a flat white painless lesion on the inside vaginal lip,smaller then a dime. Didn't look like herpes pics. I went to the doctor she looked and open textbooks and said it didn't look like herpes. She did a culture but the culture got messed up so wasn't able to be tested. Never went back to get retested because the sore went away. October 2015, Same situation same size painless only hurt when urine passed over it but it didn't hurt to pee. January 2016 same situation took about a week to heal. Recently just got another one the end of March 2016 and pretty much went away in 2 days. What can this be, I'm scared to have sex