Vag Pain

I've been experiencing vaginal pain once or twice every week or so. The pain goes away after about 30 seconds but it's very painful and I don't know how to describe the pain  but it's very sharp. When it happens I have to stand still and notice till it passes or it hurts more. :( is anyone else experiencing this or has anyone else? The pain is also in my rectum when it happens. 
•also I'm a virgin no foreign objects have been in or near my vagina 
•and thus are not pregnant
• 0 STD's