iPhone 4s will not charge

What do I do if I accidentally dropped my iPhone 4s (does not have the latest iOS software) in slush (snow and salt mixed together) and the battery won't charge? But, when I power it off it charges by itself and when I turn it on the battery drains from 100 to 90 percent in less then five minutes. Any suggestions on what to do? Also, there's nothing wrong with my charger because it works for my ipod but not my iphone.