My grandmother got phaco surgery for cataract. after the 4 days of surgery also she is experiencing pain, pricking and watering eye. is it normal?

It may be: Some mild discomfort, grainy feeling, and tearing is normal. The post-operative eyedrops greatly help minimize the discomfort. Make sure you're shaking up your drops and using as directed.

Pain after CS: There should really be little to no pain after a couple of days after cataract surgery. Call your EyeMD for an evaluation asap. Watering eye after CS is normal, especially if there is a burning sensation (usually from dry eyes) but not pain: could be inflammation that has returned, but they need to be sure there is no infection.