I inspect my 5 year old's crotch any time she says it's sore and asks me to, just like any other part of her body 
treadingwater123, you should take her to the doctor when you can - don't worry though, you don't have to make an emergency appointment. The doctor will most likely refer to a paediatrician, to see if there are signs of early puberty.
Have you noticed any other signs such as a big growth spurt or swelling of the nipple area?