What Causes Bloating,headaches,diarrhea And Stomach Pain?

last five days i feel bloating in my stomach, lose my appetite totally, i feel like vomiting most of the time after eating, sometime feel little pain in my stomach and suddenly pain goes away, most of the time headache, sometimes like diarrhea. I m really tired of these symptoms, i don know what to do? Can you suggest me what really need to do, i m really afraid.