I've had a lot of stress lately and haven't been eating a whole lot,my stomach has been feeling a little nauseous,not vomit and i'm curious,what is it?

Gi Issues: As described, it may be you simply have a "nervous stomach" from the stress you are having and lack of adequate nutrition does not help. Viruses are also possible that can cause a "viral Gastroenteritis" which causes an upset stomach and nauseousness, sometimes with or without vomiting. Best wishes.

Anxiety + nausea: Many people feel stress and anxiety as butterflies in their stomach or mild nausea or even pain. Try slow breathing while relaxing. See if any stress can be put off for later, ie. not urgent. Try exercising and walking for stress relief. If nothing helps, please see a physician to rule out ulcer or gastritis. Bland foods. No ibuprofen or aleve (naproxen) or aspirin right now. May try prilosec or prevacid OTC