Can gastritis cause excruciating pain in the upper abd area that spreads the entire abd and mid to low back feels like strong gas pains us good?

Yes, it is possible. And you can try Prilosec or prevacid (lansoprazole). But if it travels to right lower quadrant, it could be appendicitis. But excruciating pain is not common with gastritis, it sounds more serious like pancreatitis or kidney stones. Tough to say what is exact cause, but if it is really that bad, go to the emergency dept now.