I know it's scary to consider all the possibilities, but you're 20 years old, and you need to take responsbility for your sexuality and your health. Ask yourself why you're frightened of seeing a doctor. You'll need to get over this and find someone you can trust, because over the course of your life, you will need the help of doctors at various points. So where does this fear come from?
No one can tell you why you're in pain without examining you. There are hundreds of possibilites, ranging from subconscious fears to physiological conditions. There's only one way to find out: see your gynecologist. If you're not comfortable with your current one, check with your local Planned Parenthood or women's clinic, where most of the staff are women. I generally find that women in their 20s are more comfortable with seeing another woman. Best of luck to you. Dr. J
go to the doctor not to worry