Thanks for your query.
The mouth watering with saliva and vomiting only at a night and weakness id indicative of a condition called GERD.
In this condition, the gastric acid come up in the esophagus and the throat and may need to be vomited.
I would advise you the following:
Get a course of PPI like Pantoprazole or Ranitidine, Antacid every 3 hours; good sleep of 6 to 8 hours, no anxiety or stress all help you to get alright.
If this does not help much, then you have to undergo tests of Barium swallow and upper GI Endoscopy to ascertain the diagnosis.
Hope this helps you.
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