Hello and welcome to healthcaremagic. Seems that you have a benign cyst in the vulvar region. Cysts develop as a result of blockage of the draining pathway. They can increase in size because of accumulation of contents behind the block. The likely differential diagnosis are: 1)Mucous cyst 2)Bartholoin or skene duct cyst 3)Epidermal inclusion cyst. Bartholin cyst is the most common variety. The bartholin glands are located on each side of the vaginal opening and secrete fluid that lubricate the vagina. Sometimes the openings of these glands become obstructed, causing fluid to back up into the gland. The result is relatively painless swelling called a Bartholin s cyst. Small, asymptomatic cysts simply be observed over time to see if they grow. For mild symptoms like aching (as in your case) you can so sitz bath(soaking the area in warm water) for 2-3 days along with pain-killers. Sitz bath is usually effective. A Cyst can become infected, forming an abscess. If it becomes painful/tender, or you experience fever then it suggest infection of the cyst. In that scenario make an appointment with your gynecologist right away. regards