What Causes Nausea And Deep Pain After Insertion Of Nuva-ring?

Hello, I am 17 and I've been with my partner for about 18 months now. I was on birth control for about a year up until November of 2011. I was due to insert my next Nuva-Ring on November 20th but I didn't have it with me so I never started my birth control. I had unprotected sex multiple times and took an emergency contraceptive on November 24th. My partner and I had unprotected sex after this as I had assumed we were safe. I was due to get my period on December 16th but it never came. I went into Planned Parenthood and took a pregnancy test on December 16th and it was negative. I continued to take five more pregnancy tests over the next two weeks and all came back negative. I've been trained as a peer educator about birth control and with the things I know I thought it would be okay to insert a new Nuva-Ring, so I inserted it on January 1st. I am worried because I have been waking up with nausea. This morning I woke up nauseous and vomited. Also I have been having this deep pain inside and nausea during sexual intercourse the past few days; unbearable pain that makes me feel like I am about to vomit. If you have any advice for me it would be greatly appreciated. Thank you,
Worried