Any size stone, if causing obstruction for more 10 days, need surgery to remove it. As further obstruction lead to irreversible damage to kidney. Hydronephrosis and persistent pain are sign of obstruction. Excess Fluid are of no use during obstruction but have definite preventive role. Medicine can be tried for limited time with hope to pass stone , but never gives guarantee of passage.

If its causing swelling in kidney Then surgery is required (URSL)

Stone of this size is passed in approximately 50% of the patients, remaining 50% need surgery. What will be destiny in your case time will tell. It’s depend on how frequently and how much severe pain you are having. Weather that is being controlled by oral pain killers or needing injections. Last thing is infection/fever, in this situation you have to treated intensively to remove stone .