After years of enjoying and using tampons, I now cannot do either without a sharp knife pain. Help?

You could be hitting your cervix, which is why it hurts, but I don't know why it would start to hurt all of a sudden after years of activity. I know this sounds crazy, but maybe see a chiropractor. I know that when my back or hips are out of alignment, I get pain from thrusting during . I hope that helps. If it doesn't, see a regular doctor. Good luck.