Vomited three times saturday night. have now had for several days an empty feeling in my stomach that is temporarily relieved when eating but then comes back soon after along with burping. what could this be and what otc medicine could help?

You probably have acute gastritis which could be due to a viral infection or food poisoning or alcohol intoxication. Stomach acid exacerbates the symptoms but food relieves it because it functions like an antacid and neutralizes the stomach acid. You can take antacid liquid which also contains simethicone such as mylanta, 10-20 cc, 4 times a day (before meals and at bedtime) for a couple days.