What Causes Sore Spots On The Vulva After Intercourse?

Hello, I have a query regarding women's health. Recently, I seem to be getting some sort of a sore spots on my vulva after sex with my husband. There is only one or two sore red spots that sting whilst going to the toilet and sometimes when sat in certain positions. They always aoocur on the same place and go away on their on within a week but they have started to re occur every now and then. What do you think they are?