Gosh, sounds terrible. That bad that they send you to the ER! I have had very painful, significant contractions. A little different than those I had during child birth as that felt like my insides were ripping (and massive vaginal pressure as well) but I have had really bad cramping contractions. Let me ask you this . . . are you absolutely sure these are not gastrointestinal in nature? Is it only with your period? Just a little more info to further our discussion would be helpful!
Heavy and swollen vagina, or uterine cramping? The two would possibly be from different things. If it's your vagina, have you had a lot of unfulfilled sexual activity lately? That can cause the whole vagina to swell up so much that it feels like you're walking around with a biscuit in your underpants. But if it's uterine cramping, has any doctor recommended Ponstel or another anti-prostaglandin? Uterine cramps can be like angina, except it's the uterus and not the heart. The pain comes from the cramps squeezing the blood out of the muscle and gripping so tight that the blood can't get back in. An OTC anti-prostaglandin is Advil or Nuprin, you might try some next time this is happening just to see if it has an effect.