Chronic nausea.stools usually black/maroon but not always.today stool was covered in something that looked like a wet tissue but wasn't mucus.any idea?

Probably an ulcer: Your symptoms of nausea and black stools (which we call melena) are very suggestive of a peptic ulcer (either gastric or duodenal). If left untreated, life threatening bleeding or perforation could occur. I would recommend immediately starting a proton pump inhibitor like prilosec OTC once daily, 30 minutes before breakfast. I would also make an immediate appointment with your PCP.