Glad your lithotripsy got the stones. Egads about all the sand as that's kinda like peeing ninja stars. Thank god for vicodin. You know the drill: drink plenty of plain water to flush it out.
Did he leave the strings just hanging there like a tampax string? Geez. My strings were knotted, curled and well taped to my lower abdomen for the stents I was allowed to remove myself. (The time there was enough damage that it had to stay in for 2 nasty weeks so he knew he'd remove it himself, he left the string inside the bladder so I couldn't do it myself.) Although freaky, pulling out one's own stent is far less painful, traumatic and expensive than having them pull it out for you so get the hand held mirror. I assume you've done this before but if not, it's easier if you have a full bladder and pee at the same time as you pull.
Good luck and hope the pain eases up fast.