Might be a problem with your Digitizer/LCD. You have the option to replace the digittizer itself and try or you can also replace both the LCD and the digitzer and see if that helps your phone.

There is probably still some water left in your phone. Try shaking your phone to see if you can hear some water swishing around. If you do put the phone on a jar of rice. make sure The phone is submerged in the rice. ALSO make sure you tape all the points where rice can get stuck like the head phone jack and the charging port.

Try changing the LCD Display.