I think you should be persuing an explanation from his medical oncologist as this sounds like it could be a problem caused by the chemo drugs. Has his cardiac and renal status been evaluated as it sounds like he is just retaining a lot of fluid, hence the weight gain. Is he short of breath? Insist on answers, it your right as a healthcare consumer. Good luck.

Caregiver to husband Dx. Stage 4 SCC of gingiva with 3 nodes pos. Partial mandiblectomy with bone graft from iliac crest Dec. 2006. IMRT x30, Cisplatin x3. Completed Tx. March 15, 2007. Osteonecrosis & removal of graft & plate Oct. 2007. Recurrence of SCC Dec. 2007. Deceased Jan. 17, 2008.