What Causes Abscess In Vagina?

Hi I am 25 yrs weight 175 and am 5 ft 8" and am suffering with an abcess on my vagina for a number of yrs now it got swollen to the point of not walking , I had to go to the hospital numerous times to get it cut because of how painful it was, I had a surgery done on me in march of this yr and since that time the swelling never went down. Could u tell me what is the cause of it