It is most likely to be some form of allergy or dermatitis
, and the commonest causes of this in this area is a reaction to something you are coming into contact with.
This could be your new underwear which has some synthetic fibers in it and they could cause this reaction.
Or it could be a vaginal deodorant or spray if you use one, or even a bath shampoo of some sort.
You probably know that this is a very sensitive region and you should be aware that all new materials or chemicals may cause some allergic reaction
So think about whether there is something you are coming into contact with in this region that might be causing it.
Remove that factor and voila – your problems are solved!
bt if its itching it could be a
consult nearby gyneacologist.