Do you have problems inserting a tampon? Is intercourse painful or even impossible? Do you have pain with internal exams? There are a variety of things that can contribute to this problem. No matter what, it is not normal to have pain and you can get help for this.
Remember your vagina is muscles. Just like you can get tight muscles in your neck or back, you can have tight muscles in your vagina. Vaginismus is when you have involuntary muscle spasms in your vagina making insertion of anything painful or even impossible. There are various reasons that pain or tightness in the vagina may develop. It could be from a traumatic past experience that makes it difficult for your body to relax in that area. This traumatic experience may be from sexual abuse, a painful pelvic exam, or pain trying to insert a tampon. One single negative experience can make it difficult in the future for the muscles to relax and this contributes to them spasming. Pain in the vulva/vagina might be from an infection that has irritated the area. Generalized anxiety or stress may also contribute to the problem. Also, hip and back problems may contribute to vaginal pain. Or it could be as simple as it's just the way you were made. Some of us are naturally tighter in our hamstrings or neck; you may be prone to tightness in your vagina.
So what can you do about it? First of all, tell you doctor and have it evaluated. Then find a pelvic floor physical therapist. Most women with this problem have no idea how to relax or tighten their vaginal muscles. You should have voluntary control of these muscles but when you have pain, these muscles tend to have a mind of their own. In physical therapy, you will learn how to coordinate these muscles. The physical therapist will teach you how to relax your vaginal muscles and stretch them so that tampons are possible and intercourse isn't painful. No matter what, please seek help. A pain in the vagina is not something you should have to live with.