I am Dr. Arun and will be helping you today.
I am sorry that your question was unanswered for long.
Your symptoms are suggestive of Hiatal hernia with acid reflux (GERD / gastroesophageal reflux disease) with resultant reflux laryngitis. Following investigations may be able to confirm it (suggested some by your GI specialist);
1) Barium esophagography
2) Ambulatory 24-hour pharyngoesophageal pH monitoring
3) Upper GI endoscopy
4) An inspection of the larynx by laryngoscopy which may show laryngitis.
Since you are not responding to the medications; Nissen fundoplication surgery may be needed. Following specialists are needed to work in tandem for treatment;
1) ENT specialist
Following measures are helpful meanwhile (you are doing majority of them):
1) Small 5-6 meals a day.
2) Last meal should be eaten 3 hours before lying down.
3) Avoid; fried or fatty foods, chocolate, peppermint, alcohol, coffee, carbonated beverages, citrus fruits or juices, tomato sauce, ketchup, mustard, vinegar.
4) Eat slowly so air is not swallowed.
5) Swallowing therapy by a speech-language pathologist.
6) Elevate the head of the bed by 6 inches.
7) Avoid tight clothing.
8) Apart from Acid blocker (Nexium) you may also take some antacid (Maalox) regularly.
Please see the resource;
Please feel free for your follow up questions.
I would be happy to assist you further, if you need any more information.
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