Stones Cupcake has stones

My guineapig Cupcake (rescue) we think is 2 years old has been pee blood and crying when peeing over last 3 weeks. She was put on Trim/sulfa 2 * daily and Metacam. Today we took her back and there was still blood in her pee. So they took at X-ray and found she has a stone possible more little stones in her bladder.. So they gave us a chose of surgery or try and wash out the stone with sub-Q injection and give her 30 cc on water oral daily and keep giving the meds and we see her again in 2 weeks. So we going going to try giving extra water.. Lets hope she pee it out or at least push is down so they can just use tweezers to get it..She says it was a small on.. The very hard part of it..Is that her cage mate died (April) after having the same thing and have go under to get it out with tweezers..