The red light near the earpiece speaker on an iPhone is caused when the iPhone's water detection sticker is activated. This is a small sticker on the inside of the phone that turns red when it is exposed to moisture or water. The sticker stays red until it dries out, at which point the light should disappear. While the sticker is red, you shouldn't try to use your iPhone as parts inside the phone could also be wet.
Maybe put your iphone in a bag of uncooked rice for a day?