Hello, there is nothing to worry about 2mm calculus,drink more than 3litres of water per day it will pass in urine by flushing action. While passing may cause pain, in that case take antispasmodics,, if you have burning micturation then antibiotics with urine alkalizing syrup will help, other wise water is enough. Drink 2.5 to 3 litres of water per day to avoid recurrence.