Normally a cyst of 7 cms won't disolve on it's own. Could it have burst?
Call your doctor, tell them that you no longer have pain. Maybe they will do another sono before the surgery to be sure that the cyst is still there.
Good luck to you.
I began to have lower ab pain 3 months ago which like you disappeared just weeks prior to my surgery date. Now that I have the surgery behind me, I can tell you that the source of the pain that came and went would have come back with a much larger calling card. The 17 cm cystic tumor wrapped and twisted its self around my right ovary and fallopian tube creating a huge blood clot which cause the pain. My best advice to you would be to continue to seek answers, no pain does not mean no more cyst.