I agree, it sounds like you may still have a cyst, or something else going on. I would make an appointment with your gyn (if that isn't who you saw) and tell him that you are not feeling any better. Just keep in mind that YOU know your body better than anyone else. If it is telling you something is not right, you need to listen and demand that your doctor do something. Please don't let this matter drop. Keep us posted on what is happening.
Did the doctor get the final radiologist report on your ultrasound? Are they certain a cyst is not still present? It sure sounds like one is present. Ruptures can also cause severe symptoms, but not for 4 months. Something is still there. I hope they find it for you.