I'm afraid to eat in front of my friends?

No specific thoughts pass thru my head and I didn't have a traumatic experience or anything I can think of, I just feel nervous any time I have to eat around even my closest friends. I'm not anorexic or bulimic or anything but the only time I feel comfortable is eating in front of my family or alone. When I'm with friends I start to feel nervous and nauseated, and I don't wanna eat [don't have an appetite either - the sight/smell of food makes me more nauseated]. What is this and how can I get over it?