Got Blood In Urine After The Surgery For Appendix Which Was Ruptured

Im 14 years old, female, May 2010 i had apendicitus, it had ruptured. I spent 10 days in a hospital bed vomiting and had a drain. about one week after being discharged i did tryout for cheerleading, i didnt do much, and felt fine. 2 months after i began to have sharp stabbing pains in my abdomin. Doctors said it couldnt have anything to do with the surgury. Since then it has gotten worse, in september i had 2 ultrasounds done, nothing was found i also have had urine and blood tests done within the last two and a half months. Tonight it was awful lasted for 30 minutes. I finaly decided to go to the bathroom, i could not go number 2 fully. and when i pee i always feel sharp pain on lower left side near ovaries. on a range 1-10 it is 6.After going i relized there was something in my urine. and darker colored thing about the size of a quater. if looked at closely there is bloode inside. it is not round but sort of stringy.