It sounds like a yeast infection.... did you apply the yeast cream consistently? And for several days straight?
Which yeast cream did you use?
Our Pediatrician, recommended an over the counter yeast cream with Clotrimazole in it.
There are different kinds of vaginal yeast creams, with different ingredients. If one does not work, then try another one with a different active ingredient in it.
Next, is she perhaps getting irritation there... either with her hands, wipes, not wiping well when toileting, eating any foods that are causing an irritation, too much sugar in her diet which makes yeast infections worse... since it thrives in sugary environments....?
Yeast infections can recur, as well. It is not always easy to get rid of it.
I would, take her to the Doctor, or another Pediatrician and get a 2nd opinion.... her vaginal issues has been occurring for a LONG time... 1 year as you said... that is not normal. And, the urine test she had, was 1 year ago. Time for other testing.... by now.
You could also try Burt's Bees "baby bee" diaper ointment... which for my son, this worked very well, for usual diaper rashes.
BUT if it is a yeast infection, a typical diaper cream will not work, conclusively.
Is anyone touching her down there????
all the best,
Susan