What Am I?

Clue 1:  I am a part of the human body.

Clue 2: I am inside your body so you never see me.

Clue 3: You sometimes feel a pain in me when you get sick.

Clue 4: I can have food inside me but I am not your mouth.

Clue 5: I make rumbling noises when you feel hungry.

Clue 6: I am the special sack that holds the food you eat after you swallow it.