Sounds like a skin condition. Also, you could be having a reaction to a lube you're using or what is on the condom he uses. I would get help from a professional, I'm sure they can figure it out. Oh this isn't the same thing, but I started getting a horrible rash under my arms. Switched Deodorant and bang problem solved. Could be something you're using.
Hi 555, this sounds very much like your labia major, your find this is different on all women, fi you google labia major, and look at images, you will see, and perhaps some you would like top see, but there all there.
Perhaps and not knowing your age, but you can have these tidied up when you a bit older with some surgery.
Good Luck