27, female. I have the "chaffing" area where my inner thighs rub together. After vigorous physical activity, I develop a "sore" in the chaffing area. The sore will contain a yellowish, opaque color and will be somewhat painful. After the sore goes away, it feels like a hard, tiny pebble or seed remaining in that area. It comes and goes in cycles. What is this and how do I get rid of it?