I Have Been Getting Treated For A Resistant Duodenal Ulcer

I have been getting treated for a resistant duodenal ulcer for 2+ years. Recently, my doctor switched me from omeprazole to famotidine. I'm currently taking 40 mg twice a day and although my ulcer pain is controlled, I am experiencing recurrent chest pain. I'm 61 years old, in good physical condition and the pain don't occur when I work out; however, I am getting concerned. I welcome your response. Thank you so much.