I am not saying you have Behcet's Disease. I just want you to be aware that if it's not an STD and it's not an in grown hair and you have this problem repeatedly, than Behcet's would be the other thing it could be.
There is an autoimmune disorder called Behcet's Syndrome's. It's initial symptoms closely resemble the herpes virus, causing inflammation, vaginal sores, cuts, boils, fissures, or folliculitis ( in grown hairs). I doubt you have an in grown hair that close to the clitoris, but it is possible. Watch for more symptoms. If you have this again see your doctor. For now, soaking in a hot bath will bring it to the surface so it can drain and heal. With BD other symptoms will develop weeks to years later, so it is very important that you find out just what it is that is causing your symptoms. Common later symptoms are bowel inflammation, bladder inflammation, fibromyalga or muscle pain, arthritis, nerve damage, and chronic fatigue during flares. Don't be too quick to brush it off as nothing, Behcet's disease affects people of every age and every race. It is important you see a doctor who can help you. Ask them about Behcet's Syndrome, if they don't know enough to tell you, they won't be able to tell you if you have it or not. You can also visit the American Behcet's Disease Association's website message board for further information. It is not contagious and it does not run in families. It happens because the imunne system has been damaged by something like strep throat, certain infections, food poisoning, or for no known reason. People who have Behcet's have flares that will progress if they don't get treatment. There are no tests that can tell you if you have it. Right now patients in america are not being diagnosed until they have serious injuries. It is suppose to diagnosed based on symptoms which start with the gential problems, cranker sores in the mouth at least three times a year and the last symptom, eye inflammation which may not show up for many years. In the mean the disease causes damage which goes unnoticed throughout the body. It attacks the vascular system which normallly is not detected by any blood test CT scan or MRI. Vasculitis is generally only found during surgery or autopsies. Vasculitis can cause extreme pain, blood clots, strokes, and brain inflammation among other things.
It could be an ingrown hair. A friend of mine had the same problem about a year ago. She saw a doctor thinking it was an STD but turned out to be an ingrown hair. If it doesn't go away, or if it starts oozing anything see a doctor.