There are below reason for pinworms…..
Hormonal changes and perimenopause
When your hormones fluctuate during your menstrual cycle, you might end up with drier vaginal tissue than normal, which can cause itching. But Minkin points out that perimenopause (a.k.a., that time period before you actually start menopause) is a more common reason for vaginal dryness and itching, thanks to the drop in estrogen.
An OTC moisturizer like Replens can provide relief from internal itching for three days, Minkin says, and your provider can give you a prescription estrogen cream for any external itching.
Urinary tract infections
A urinary tract infection (UTI) is a bacterial infection that crops up anywhere in your urinary tract (read: kidneys, urethra, ureters, and bladder), and will commonly cause pelvic pain, a strong urge to pee, a burning sensation when you pee, and cloudy or foul-smelling urine.
But Minkin confirms that it can also cause itching in the form of a tingling, irritated sensation, especially if the infection is located near your urethra. You need to snag an appointment with your doctor and get a urinalysis to check for the presence of bacteria (which an antibiotic can clear up).
In the past few decades, women have grown more preoccupied with the appearance of their vulvas, says Minkin—something she attributes to the trend of having less hair down there. Which means many women have also tried out some pretty unconventional beauty treatments, like activated charcoal vulva masks (basically a facial for your vagina) and vaginal steaming.
Sexually transmitted diseases (STDs)
Okay, let me preface this by saying itching isn’t really a classic symptom of most STDs, though it can sometimes be a first sign that something is up, says Minkin. From there, symptoms may progress to burning, painful urination, smelly discharge, sores on your genitals, or painful intercourse, at which point you should definitely head to your ob-gyn for a vaginal culture.
One kind of STD, though, is often associated with itching: genital warts. “Genital warts are lesions on the skin and are generally caused by the low risk types of HPV,” says Chinn. “This type of STD can shift the pH in the vagina, which then causes dryness and itching.”