Help me!

OKay i dont know wtf this is. I wanna make a movie in gmod one day i open gmod make a singleplayer game and when i look down i see my own player model? Sounds weird right? Yes i try to find out what this is i make a camera and its actually my player model not just a camera glitch but my camera model going down in the world if i look down! Wtf? Help me!

Have a nice day.