Alright, I need some advice.

I've browsed DOZENS of sites, and part of me is as confused as the other part if me is terrified.

The past few weeks, each time I attempt intercourse, I encounter a severe pain. Severe enough that I curl up in a ball and cry. My menstral has been on time, however, it's been much shorter and lighter than usual the past three months. I have back pain, not severe, but bad enough for it to slow me down. My breasts aren't 'tender' but they've felt a little odd for the past few weeks, as has my stomach. I'm twenty, and I want a child, but I've miscarried before and I'm more than a little afraid to get my hopes up.

Please help!