Vulva always raw after intercourse, sometimes it turns into a yeast infctn. what can i do other than keeping clean and cotton undies to help/prevent?

Lubricant: If this problem only occurs after intercourse it is like a lubrication problem. Find a sexual lubricant that you like and use it liberally before and during intercourse to see if this helps. If the inflammation occurs at other times then an underlying vulvar condition may be present. An obgyn should evaluate this and see what might be done next.