Hi there ~
I understand your concern. I believe that the swollen glands and pain and heaviness in the chest is probably related to a cardiac condition if the mononucleosis
is ruled out. I also believe that your infection in the stomach needs to be treated and that taking an H pylori test would be a good idea. I think that you should look into getting yourself checked up for all these issues by a good doctor.
I hope this helps. Take care and have a lovely day!