For the past 2 months my cycle has been abnormal, I have been nauseous, fatigue, had excessive gas, however a home pregnancy test was negative. The pain is on the lower left side of ny back.

YES! I have gone through this.. I was 12years old when I got it removed, I am now 14 yrs old. I have always had those signs of this since I was about 10, when I first got my period, the doctor told me I have had the cyst since I was about 3 yrs old, but it didn't start growing & causing problems till I started "growing up", I would have all the symptoms(sp) one day, then they be gone the next, so my family & I just thought it was like a one day sick thing, my signs of it were... vomiting,EXTREME BACK,CRAMPS & STOMACH ACHES, headaches, coughing up blood ( very rare), very tired. They always came close or during that "time of the month". Until July 4th, 2009 when Things got worse & I woke up screaming in pain, Doctors told me I have a 19lb cyst on my left ovary, after that doctor appointments, cards & flowers from family & friends, July 28th, day of surgery, the cyst came back to be B9. After surgery I noticed I was smaller, I wasn't big in my stomach area anymore, it was like I literally 19lbs, when I just got rid of a cyst! I know you didn't need to here my little story but I just wanted to say, get it checked out, before things get worse.