Kidney Stone. Then what will happen?

I have a kidney stone of 9mm in right ureter now, doctor said it's vertically placed so that's why you only have mild pain. Symptoms Flank pain both sides (why on left side?) If I pick something heavy I get mild flank pain on left (why that happened?) Now flank pain is not there but having pain in lower wait most of the time right side. Problems with urination begin Problem with urination flow... Sometime don't get enough speed like I used to. My question is Why I did get flank pain on left side and now that flank pain is not there why I get mild left pain if I lift heavy? Second now that stone in ureter is that something I can left untreated or do I really need to treat this Coz earlier it was in kidney so it never bothered me. How long can I leave untreated? What's the recovery time of a uteroscopy. Doctors sair it cab get out but I'd that the case that it wouldn't go out of bladder then what will happen?