Sorry to hear about your father.
In February 2008 I noticed a greatly enlarged left testicle, an ultarsound indicated a suspicious mass. In March the testicle was removed in a straightforward operation . Pathology of the tissue indicated diffuse large B-cell lymphoma. I have now completed 4 of 6 scheduled chemo treatments with CHOP + R, after which I will have 20 radiation treatmebt.. The chemo leads to severe fatigue, vertigo, and other side effects, but PET and CT scans indicate the cancer is being elminated.
I can not speak to your father's stomach situation.
Good luck
Irv