Verified answer

Yes an allergy to the fabric or maybe even your washing powder/liquid or something in your loo roll (eg. dye) or sanitary products (some people are allergic to certain types of tampons etc). And, are your knickers washed at a high enough temperature (eg. 60C)?

Whatever, you might find it very helpful to use a "feminine wash" down there rather than normal shower gel or soap - it's available in most supermarkets, chemists etc.

But if you've had any sexual contact then consider that you might well have an STI/STD, in which case see your doc or go to a GUM clinic. One can also have "thrush" without sexual contact, for example due to a dietry issue, which would be something for your doc to look into.

All the best!

Try and change the underwear you have been wearing. Try different fabric. You may have allergy to the fabric you are using now.