Hello,
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Symptoms described by you ( hyperacidity since 7 years ) suggestive for gastroesophageal reflux disease or/and associated with chronicle gastritis, but best method to determine exactly is Endoscopic examination. Regarding your diarrhea , nausea ( vomiting sensation ), meteorism ( gas ) these symptoms if appeared since three days , then can have few causes, like as a complication of your basic gastrointestinal disorder, or food poisoning, gastroenteritis viral or bacterial origin ( very frequently accompanied by vomiting, nausea, diarrhea, abdominal cramps ).Right now I would recommend you following measures: proton pump inhibitors like omeprazole or pantoprazole once a day before meal in the morning , in sever cases associated with ranitidine twice a day ( to control hyperacidity ,nausea); Oral rehydration salts every day, Probiotics, adequate fluid intake, light diet. Monitor your self for more two three days and if there no improvements or will appear additionally to diarrhea persistent vomiting, abdominal cramps, muscular pain, fever, headache, then you need Doctor consultation and laboratory investigation : stool exam and culture, urine analysis, complete blood count, biochemistry ( especially electrolytes ).All these tests will clarify cause of your diarrhea, nausea and abdominal discomfort .Additionally Endoscopic exam to clarify cause of your hyperacidity.
I wish you good luck and speedy recovery,
Hope this helps and I have answered your query. If you have additional queries don’t hesitate to ask.

Best Regards,

Dr.Mihail

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