I have a ovarian cyst/enlarged ovary thats 8.1*4.2*4.2 cm and in really bad pain what should i do go to e.r. ?

Bad pain = ER: If you cannot control your pain at home with the medications provided, then should go to the er. Also, if the pain has suddenly changed character / worsened / moved, then go to er. If "same old" pain, call your gyn, but if un-reachable, go to er.

Size: The size does require attention. If you have had an ultrasound to determine the cyst and size, then your doctor must have ordered it. Get your instructions from him/her. No need to go to er as this is not an emergency situation.