What Causes Fever And Painful Rash Below Vagina?

Hi doctor, I have a question..I have had a bad rash after my periods got over (don't know if it was the pad friction)..it's gotten worse since last three days..it's just below the vagina near the bottom part of the butt crack.. Only left side..it's reddish, slightly inflamed, warm and extremely painful..specially while sitting or lying down. Also I have had fever in the range of 100-101 F..is this just a bad case of very bad rash infection?