There are no medicines as such for melting kidney stones but some medications have been used to increase the passage rates of kidney stones. These include calcium channel blockers such as nifedipine and alpha blockers such as tamsulosin. These are available under prescription. But it depends on the size and site of stone.
If the size of the stone is small, it’s usually treated with ESWL in which shock waves are given from outside and stone breaks into small pieces. On the other hand, if the stone is quite big, then the surgical removal of the stone is a better option. Please do continue to drink lots of water for it does facilitate at least in preventing the formation of new stones if not the flushing out of the present stones.
It is very difficult to precisely confirm a diagnosis without examination and investigations and the answer is based on the medical information provided. For exact diagnosis, you are requested to consult your doctor. I sincerely hope that helps. Take care and please do keep me posted on how you are doing.