I Have A Stabbing, Acidic, Nauseating Pain In My Upper

I have a stabbing, acidic, nauseating pain in my upper left abdomen. I have had an upper endoscopy, 3 yrs ago. it has been determined that the results lead to the conclusion that my tummy is afflicted w/ gastritis. I currently take Protonix on a daily basis. However, regardless of my daily dose, my 'flare-ups' , are intolerable. What may I possibly do? Please help me.