Nose ring wont come out and it hurts! What can I do?

I just got my nose pierced 3 days ago but instead of a stud I got a ring as in a hoop nose ring. I want to take it out to put a stud in but the opening is same thin as paper so I cant get it out.. I hurts so much, I'm in tears right now as I type this. The man gave me a 18/16 gauge ring.. it too big i need it smaller... This is the the second time i have been unable to take off a piercing from this piercing store. I'm in so much pain. How do I get it off?!! We tried to use small bolt cutters but it hurt to much. What Can I Do?