Hi thanks for your question.
Commonest cause of pain in the middle of abdomen above rib cage with nausea is gastritis
that is inflammation of stomach.Gastritis is caused by excessive acid production secondary to a variety of factors like cigrette smoking,alcohol,spicy food and infection of stomach by a bacteria called as H Pylori.Gastitis is also associated with excessive salivation
..You can take antacid,and proton pump
blockers like pantoprazole
.Consultation with a physician is advisible who may perform upper G I endoscopy on you to determine the cause of your symptoms.
Hope this answers your question.