Iphone 4s right side not working?..

I got my aunt's former iphone 4s before yesterday and she wet it. It had no damage whatsoever, but, the day I started using it, it would sort of twitch. When I touch the left side of the screen, its perfect, but just hovering my finger over the right side, it starts twitching and choosing other things on the screen that I do not want to select. Yesterday, it happened about 3 out of 10 times that I used it. Today, the right side's problems have been constant. Please help!!!!!!!! Could it be the water? Is there a way to fix it?