What should I do about my terrible pain? Should I go to the ER, and risk christmas? Please Help Me!?

HI, Im a 15 year old girl who is going thru alot of problems right now. I have terrible abdominal and back pain in my lower left, and I feel like I am being stabbed. I am scheduled for a colonoscopy tommorrow but my pain is really terrible right now and I have a fever of 102. My mother is afraid too take me too the hospital because she is afraid it will mess up my colonoscopy. I really want to go to the ER but I am afraid I will have to spend christmas in the hospital. What should my mother and I do?