30mins after eating my gut sounds noisy.suffering from fatigue&weight loss.colonoscopy clear, worried about smallcell lung cancer secrting hormones?

Unlikey: Small cell lung cancer is not subtle. This would be way down on my list of possibilities, along with other paraneoplastic GI syndromes. With fatigue, weight loss, and a rumbling gut, I'd check you for malabsorption / maldigestion, gluten enteropathy, maybe Whipple's, Crohn's, giardiasis, pancreatic insufficiency from tumor / adult onset cystic fibrosis, a few others.