Stuck inside a rock - glitch

You could try to Fast Travel if you're outdoors.

Beyond that, you'll probably need to load a new save if you're playing on a console.

If you're NOT playing on a console, just use the developer's console by hitting "~". Use the code "tcl" to enable no-clipping mode, then close the console by hitting the tilde key again. Move out of the rock, then repeat the key sequence to return to normal mode. I'm not much for cheats, but this game has made me do that several times.