My nose ring won't go in anymore. It hurts & seems there is no whole on the inside. what do i do?

After having the piercing for five months I thought it would be fine to replace the nose ring. Since then I've changed it a couple times. Each time its difficult and it hurts. Yesterday I made an attempt to replace the ring again because the one I had wasn't every comfortable and I have been unable to get the ring through the whole. It seems that the whole had closed on the inside because I can't get the ring through to the other side of my nose. What should I do?