There are a few things that could be causing this symptom for you, but not all of them are sexually transmitted.
Our skin can sometimes be sensitive to things like soap, fabric or perfumes that can cause irritation. If you have recently changed a part of your hygiene routine or underwear, you may want to consider if that could be a root cause of the irritation. If you are physically active, play sports or sweat a lot, this can also cause irritation. Be sure to hit the shower and wash your clothes/equipment after physical activity.
Alternatively, this could be something that any health care practitioner can help you with, be it a fungal infection or scabies or pubic lice. STBBIs (sexually transmitted and blood-borne infections) are more commonly painful than itchy. But routine STBBI testing is always a good topic to bring up with your doctor or nurse is you are sexually active.
The difficulty is that many common symptoms may be caused by any number of common infections. The only way to know your STBBI status is to get tested. I’d recommend seeing your family doctor, or even a walk-in clinic if you can’t resolve it by using a gentle soap or over the counter anti-itch options.