If your cyst has grown, it could be putting pressure on your other organs or nerves causing pain on the left side. It is not uncommon for even a small cyst to cause a great deal of pain. It can also cause back, hip, and sharp abdominal pains. Like Shelly said, you should probably give your doctor a call and see what he thinks. Hope things get better soon.
Kasie
How long has it been since you had an ultrasound? It is possible you have developed another cyst. If you have a condition like endometriosis, that could be the cause of both your pain on the left and your cyst on the right. You should call your gyn and get checked again to be sure you haven't developed another cyst. I hope you feel better soon!
Shelly