What is going on with my voice?

When I talk people have a hard time understanding what I say... even when I try my hardest not to mumble, my voice sounds very gravelly.. you know when you first wake up maybe too early and your voice is crackling - it's like that except 24/7. Gets worse if I'm under stress or talking to someone I don't know. Any idea what is causing this? It also feels as if I'm talking through my ears... not sure if you can understand that, but when I talk it's even hard for me to hear what I am saying, obviously I know what I am saying but the actual sound just sounds very messy.