What Causes Raised Sore On Labia Minora?

I had a raised sore on my labia minora as well as a burning and itching sensation in the area. I called my OBGYN and they told me to apply some Desitin cream. The Desitin burnt me. After this I had blisters all over the area and in turn was misdiagnosed with herpes. Now that herpes has been eliminated as a possible cause, could it have been ringworm? I had ringworm about a year ago and am consistently in lake water and wet clothes for hours at a time.