What Causes Belching And Pain In Stomach, Chest And Legs?

I have bad pain in my stomach and pain in my chest and legs.. i have a hard time sometimes with bowel movements and i felt something pop in my stomach and all of a sudden i started having really bad gas and loose bowels then i started belching and the smell that comes from my mouth and breath is really bad it makes people around me feel sick to smell it when i talk. can you please help me?