Hi, My Stomach Hurts And It's Not Period Pain Or

Hi, my stomach hurts and it's not period pain or food poisoning. The pain radiates through my back and my head hurts too. I feel like throwing up and I fart without trying. My fart stinks and my stomach feels heavy and bloated. The pain in my stomach comes and goes every 10 minutes and it is very excruciating. I feel weak and don't want to get out of bed. Plzz tell me what medicines should I buy. Thank you.