Treated w/ luprin for endometriosis on 10/29. Developed an ovarian cyst in nov. Started having pelvic pain a couple if days ago, could the cyst be causing the pain?

Yes. Lupron (leuprolide) acts to temporarily shut down your own production of ovarian hormones and this causes endometriosis to shrink/regress. If given during the first half of the menstrual cycle it can cause a "flare" effect and cysts can form, the cyst could be the cause of the pain, and if it is severe you should see about getting a sonogram.
Possible. There are many things that can cause pelvic pain. You should seak medical care.