Anyone know what's wrong with my audio jack?

So I've had this computer for about 2 years now, got this when I graduated High School now I'm going into my junior year of college. Out of the time that I've had it I had to replace the hard drive once, and nowadays the headphone jack is giving me some sort of strange feedback. I read other posts regarding systems preferences regarding headphones and it works just fine. The weird thing is that whenever I plug my headphones in to the audio jack, I receive a lot of unnecessary feedback. I'll hear buzzing, static, and my sound is all the way at max volume but it sounds as if it's at the minimum. Whenever I jiggle my headphones the static gets louder, but that doesn't seem to solve the problem or give an idea to what's wrong.

Props to anyone if they know whatever's going on with my stuff. Thanks