Need to check the location of the stones. At that sizes they are unlikely to be drop down with medical treatment. If it’s anywhere in the tract then need to remove them. Drink a lot of fluids, 4-6 litres per day. Lot of water, barley water, buttermilk, lemon juice, orange juice etc. avoid cabbage, cauliflower, tomato, non veg an reduce intake of green leafy vegetables. And fluids need to be taken every hour rather than gulping 3-4 times a day. It would be better if you can post the ultrasound report.

Continue taking good amount of water ,and consult a nephrologist for evaluation of any renal disease i view of stone forming at such a young age