Dropped iPhone in water and volume keeps going down?

About a week ago I dropped my iPhone 4 in water. I removed it immediately, patted it dry, and put it in rice for a while, however I didn't put it in rice right away because it seemed to work fine. After taking it out of the rice the screen was a little water damaged but that got better on its own and the home button was glitchy but now it works fine. My only problem now is that the volume keeps turning down on its own, whether the headphones are in or not. If I try to turn the volume up I can see the volume bar shrink to nothing. Usually, the shadowy gray volume box remains on the screen like its continuously being lowered. Ways to fix this issue would be great, thanks!

I'm not sure what's wrong with it, but your best bet is it to take it to your nearest phone repair shop and ask them to take a look. You don't have to actually get it fixed, but if you ask the person what's wrong with it, they might be able to help you and give you some advice.