What Does A Lump In The Groin Area Indicate?

I have a lump under the skin between my vagina and thigh. It is basically on my groin muscle. It appeared about two months ago and was really small (I thought it was a zit at first). When I first got it it stung to the touch. It was also discolored, purplish. Now, it has grown and is roughly the size of my thumb nail. The color has gone down a little and it no long stings to the touch but sometimes my underwear will pinch it and that hurts. Should I go see a dermatologist, a gynocologist, or someone else?