16mm is very big size for a gallstone. Gall bladder stones do not get dissolved with any kind of medications. Rather with time they keep on growing and may lead to severe complications.
The only safe and the permanent solution is laparoscopic surgery which is a very simple safe amd permanent treatment optikn with no side effects in whole lifetime
Next Steps
please visit a laparoscopic surgeon who will explain you all the details related to surgery.
im case if you are in Pune you can come down to Columbia Asia hospital at Kharadi and I will tell you all the treatment part in a detailed manner.
Health Tips
avkid oily/spicy foods as these aggravate pain that is caused by the stones