What kinds of things can cause unexplained chronic nausea?

Lots. See your doc: Are you pregnant? Gut causes can include inflammation, ulcers of stomach, duodenum; parasites, tumors, pancreattic issues, enlarged lymph nodeis or spleen (varhious causes), colon, gallbladder or liver conditions, diabete, thyroid disease, elevated blood calcium or glucose, other hormonal, adrenal, gyn disease, sinus, inner ear, brain issues, meds, excess coffee, suppl, drugs, iron def etc. See m.