there's nothing wrong with going back to your peircer if you're worried about something that they did for you.
sometimes [ especially with cartilage ] the skin doesn't quite " fuse " with the new hole in your cartilage right away. sometimes the actual jewelry can poke UNDER the skin opening if it's a bit loose. the angle is very important when you try to slide it in. rings can be difficult in tight places like a nostril.
i would suggest taking a warm, damp cloth and holding it at the peircing for a few minutes. this generally relaxes the skin and can make inserting new jewlry a little bit easier. lubricant is your friend.
also, it *might* be too soon. does it hurt when you try to insert the jewelry?
try the warm cloth trick and if it still isn't working, maybe you should wait a while. ive never had a nostril peircing so i don't know beyond that.
good luck!