Hello,
There is not a single cause which triggers genital psoriasis, however it can occasionally be triggered by: tight clothes which rub the skin, contraceptives - sheaths, caps and spermicides, sanitary towels or tampons, harsh toilet paper, thrush or sexual
It is very difficult to precisely confirm a diagnosis without examination and investigations and the answer is based on the medical information provided. For exact diagnosis, you are requested to consult your dermatologist. I sincerely hope that helps. Take care and please do keep me posted on how you are doing.