Do i need immediate care? severe pain in my abdomen pelvic and lower back. i've already been diagnosed for large ovarian cyst but don't know much else

Possibly: If you are having severe abdominal pain for longer than a hour you should probably see a doctor and get checked out. Could be the ovarian cyst but could also be the appendix, your aorta, a hernia, or numerous other bad things...

Yes: Like Dr Pool said, it could be many things. Given your ovarian cyst history, ovarian torsion would need to be ruled out.