For the past month or so when me and my boyfriend try to have sex he says it feels like my vagina is "closed up." Now I am on my period and when I try to put my tampon in it feels like it is just being pushed right back out. I am 19 and have been using tampons for 5 years and never had this problem before. I felt in there to see whats up and at the back of my vagina I can feel like a big circle I guess this is my cervix? But it feels like its really big or something and my vaginal wall is really tight around my finger when i try to feel around. Whats wrong?
Yes, that should be your cervix. It feels like the tip of your nose sticking out at the top of your vagina. When you menstruate, it is hard and stiff, low in your vagina and the little hole in the middle is open to allow the flow back out.
You have a lot of muscles around the vaginal entrance. If these contract when you try to penetrate it, it can feel that blocked. It often happens when you think it is going to be painful (just like your eyes lids close when something comes close to it). Or if you do not relax these muscles it can be very difficult to get anything inside.
Look at 'kegel exercises' on the google to see which muscles these are.
Relax, relax and relax. Try after a nice warm bath. Use some lubricant on the tampon applicator (Vaseline or personal lubricant will be fine - the only time Vaseline is fine to use there). Use the smallest tampon that will last 4 hours. Try one with a plastic applicator (like tampax pearl). Take it very slowly, a little bit at a time. Make sure you squat or open your crotch enough to take the pressure off the muscles (foot on the toilet/bath or splitting your legs with your feet next to each other). If it is not painful, keep on pushing and wiggling the applicator to get it right up there.
If it continues, talk to your doctor to make sure there is not some physical problems.