She might have an infection. It's not a good idea to out anything in her bath water. Take her to the doctor for evaluation and information on what to do.

When she is taking baths, do you usually make it a bubble bath?
Have you switched soap brands?

I was a nanny for 5 years and the little girl developed this problem as well. She was 5 at the time. It turned out that she was allergic to the bubble bath solution.

Just a thought.

if she has an infection, after you take her to the doctor and get dr.'s okay maybe a sitz bath will relieve any pain/itching. i know that a sitz bath is tap water and baking soda...don't know the ratio so ask dr.

A lot of children are allergic to bubble baths (my daughter) and it can actually cause urinary tract infections and yeast infections. I had a lot of yeast infections when I was younger, and I would take hot baths with baking soda. My doctor told me to eat a lot of yogurt as well. Even though she is 4, do not hesitate to use Desitin, or a medicated powder to protect the area and keep it dry.