Hello and welcome to HCM.
Thanks for putting up your query over here.
Yes,cause of excessive phlegm is gastro oesophageal reflux disease.
If I were your treating doctor ,I recommend,
-Visit to gastroenterologist/surgeon as radiological studies or upper GI
endoscopy will be necessary to diagnose the disease with its severity.If needed,surgical repair may be considered.
-Cap
omeprazole with anti emetic like metoclopromide once in morning help in decreasing the reflux.
-Avoid hot,spicy,high fat content food.Avoid alcohol and caffeeine.
-Keep your body weight within control by healthy diet and brisk walking for 30 minutes everyday.Avoid doing dieting.It may increase your problem.Dont skip meals.
-Have meals atleast 3 hours before you go to bed.
Sleep with head elevation.
Hope this information helps.
Thanks.