Yes, diverticulitis is not limited to the left lower quadrant, especially in more severe cases. If the condition ascends up the colon to the splenic flexure, it can cause pain as high as your left upper quadrant. Other possibilities include pancreatitis, gastritis, an enlarged spleen, lower lung pathologies, just to name a few. Some more simple explanations include gas/bloating. You should get a follow up CT scan of your abdomen to evaluate your colon as well as a routine screening colonoscopy once after the age of 50 every 10 years, might be a good opportunity to check what is going on in your colon. Annual fecal blood testing is also recommended. Try to avoid eating seeds, high residual bulky foods (celery, carrots), and increase your fiber diet. If you are currently on two antibiotics I would assume you have recently had an acute flare up. Being exposed to second hand smoke can mildly increase your risk for lung cancer, but not to an appreciable extent that would suggest routine screening. Please clarify where your pain is radiating and if you have had any abdominal surgeries, bowel obstructions are common if you have chronic diverticulitis and a history of surgery of the abdomen. As always, follow up with your doctor for a more comprehensive evaluation. Hope this helps.