It can take a long time to heal. Even though the h-pylori is probably gone, your stomach now has to repair. Even on omeprazole your stomach produces a lot of acid, the h-pylori will have weakened your stomachs defenses and now its sensitive, over time it should improve.
Its probably not an ulcer, but try taking some Tums when its bad to see if that helps.
Also what are you eating? I have frequent bouts of gastritis and there are so many foods that aggravate it the list is endless.
GERD, Anxiety, Depression, Rolling Hiatus Hernia, Esophageal Hypersensitivity