Hi there. It's not uncommon to have exzema, dermatitis or psoriasis in the pubic area. It can be quite itchy. My suggestion is to not treat this on your own but to see a doctor to determine if any of these conditions are going on and if so, they'll prescribe a topical medicated cream to resolve it. Good luck
Even though you have not had any sex for the last 3 months, heck for any crabs which are transmitted through sex.
You could make an appointment to see your own doctor or go to the GUM clinic to get checked out.
Severe itching can be caused by lots of different things, and as you had been sexually active, it would be wise to get checked out for any sexually transmitted disease. The doctor would also be able to take a swab to send to the laboratory to identify if there is any bacterial of fungal infections. The treatment is different depending what the underlying cause is.
At home, do NOT use any soaps, bath or shower gels. Baby washes may be fine or soaps that have the same pH level as our skin. Do not use feminine sprays. Only wash your undergarments with non biological detergents. If you do have sex use the latex free condoms.
Bathing with 3 cupfuls of Epsom Salts can help, by neutralising the pH level on the skin. And as a home help remedy, apply natural set yogurt to the area after you have washed and gently dried it can also help to alleviate the itching and cool down the pain.
Make an appointment to see your doctor, or go and get checked out at the GUM clinic.