Have chronic low rt pelvic pain (10 mo) & recently had surgery. They found endometriosis, but not on the right side. I'm still having the pain.?

Likely endometriosis. Most patients have very good results when treated surgically for endometriosis, at least initially. Unfortunately though, many do not - and most of those who do eventually experience a recurrence of their pain requiring additional treatment. If your pain was not inproved at all, you may need to have a colonoscopy to evaluate the bowel and/or see a urolgist to rule out a bladder problem.
Could still be endo. Endometriosis is one of the most common causes for the reproductive-age patient (patients who have menses) to have pelvic pain. It is fueled by estrogen. Depending on the stage of your endometriosis and the type of treatment you are receiving, the pain can return this quickly, even in 10 months. You need to discuss with your gynecologist.
Rlq pain. In younger women the appendix could be involved or be the cause of some pain in about 60% of the patients with endometriosis. This pain could be a referred pain from the bladder due to a condition called painful bladder syndrome/ic, or even from the pelvic foor muscles or abdominal wall trigger points.