Hi there this is Dr. Jody Navitsky and I realize that it has been a while since you posted your question. If you would like to chat with me I am available and would be happy to discuss this with you.
I'll wait a bit before leaving you a generic answer just to see if I can catch you so we can chat. Thanks!
Hi again sorry I wasn't able to catch you online to chat, you may have already solved your issue but just in case I will leave you an answer and some advice.
So 3 year old girls can get yeast infections in the vaginal area characterized by extreme itching (you see her scratching) and maybe some vulvar redness along with the typical cheesy white discharge. Usually the yeast tend to be limited to the vulvar area and not as internal as they may be for an older woman.
The creams to treat this are over the counter but as there are other things that may cause this I would use a bit of caution before starting one as it can alter the vaginal flora and cause more problems if she doesn't have yeast overgrowth. That said I don't always send a culture when I see it clinically but I do try to although usually I start treatment based on the clinical picture.
If you choose a cream any one over the counter such as miconazole or clotrimazole (2 most common) are fine and are used 2x a day for at least 1 week if not two.
They are used externally only and not internally.
Other possibilities include run of the mill vulvovaginitis (basically a subtle infection/irritation of the external vulvar tissues), that is very common in this age group when they start taking care of bathroom duties by themselves.
This usually has more redness associated with it and may even be painful. The odor tends to be different from what you normally see for her (usually smelly) and there usually is discharge that can be white or yellowish and you may even see it coming out of the vaginal opening or accumulating on her underwear.
We recommend sitz baths and improved wiping by making sure she is totally dry (I recommend teaching her to squat so that she can dry inside the vaginal area sufficiently), wiping front to back, no soap to the area or bubble baths, cotton underwear, open air time to the area when at home (walking around with just a dress and nothing covering her vaginal area).
There is also a strep infection that girls can get in the vaginal area but again I would expect more pain and redness rather than itching with this. The redness is very frank and noticeable.
All in all today I would give her a few Sitz baths (warm water only to sit in no soap), make sure you are wiping for a day or so and then reassess how she is doing. If the itch is still there or if she has been sitting around in a bathing suit or sweaty underwear now that it is hot (set up for yeast) than she may need treatment for yeast.
I hope that this information is helpful to you! I will be signing off for the evening (I am in Spain) in a few minutes but please let me know if you need further assistance tomorrow. Thanks and I am sorry again that you had to wait!