Gastroparesis (delayed gastric emptying) can cause nausea without vomiting. Gastroparesis can be confirmed with a gastric emptying study.Also, some food intolerance can cause nausea.
Eating more frequently, nausea, and vomiting are all signs of pregnancy. So is the need to urinate more frequently, tender breasts, and sensitivity to certain smells or having strange cravings. If...
Water is always a good option. I would avoid anything really acidic or cold. Different people find different things difficult, some people find carbonated drinks (like soda) easier on their stomachs...