Can you tell me what to do if i vomited clear liquid out of the blue. any ideas?

Find cause of vomit: Nausea/vomiting may be gi-related (food poisoning, peptic disease, gastroparesis, due to biliary &pancreatic disease, gas/bloat syndrome, small bowel problems. Consider "central" causes: motion sickness, vertigo, migraine headache, brain problems (some very serious). Also, rule out infection (?UTI), medication side effects, pregnancy, bowel obstruction, "acute abdomen" &even reaction to stress