NuvaRing - We had sex on June 24. My period came on July 4th. It was lighter & it only stayed on 3 1/2 days rather than 5 full days with spotting on the 6th day. I spotted the 3rd & 4th day & started my nuva ring on the 6th day .. the first two days i had bad back & abdominal pains . I have been feeling sick with a lot of body pains for the last week with nausea. Should I be worried about pregnancy or changing my birth control??