Question: Husband had 1 black tarry stool then a grey watery stool about 14 hours later. Being treated for GBM and possible viral infection. First email has more details.

My husband has Glioblastoma Multiforma. He is on Keppra daily, a lot f dietary supements such as D3, K2,C, Papaya Enzymes, etc. his two chemos are Temador 5 days per 28 days and avastin infusion every 3 weeks. For a month now as we are trying to get hm off the steroid dexamathasone he has been fighting what seems like a cold. Abut 30 days ago he was on an antibiotic and then yesterday he was given a z-pack prescription. Last night he started gagging and dry heaving. This before has to led to what seemed like a seizure the two times steroid has been removed completely. However he had no visible seizures but has continued the deep coughing and dry heaving with very little productivity and extreme exhaustion. Overnight this continued and this morning he had an extreme headache as in he could not think. I went with giving him the .5 my of steroid as advised by Nuerologist Oncogist. This seemed to ease the headache slighty and he slept. Later in the morning he told me he had a black tarry bowel movement. At this time I made caps to his oncologist team and made plans to take him to the emergency room. I care the oncall and clarified I could wait a few hours as he is very stubborn and was refusing to go until I got my sons orthopedic appointment completed (our grown son broke three bones in his foot last week and the next day is when my husbands cold/flu like symptoms started getting worse). I got an ok with that. After I returned home he was sleeping and I allowed him to sleep a little while. When he got back up he was still feeling the headache which was at a 10 and he was saying about a 7. The coughing had reduced a little however the gagging increased but he was getting some mucus coming out. He then went to the bathroom and had a loose to watery stool he states was grey. I got myself and him ready to visit the hospital and almost out the door and he said he was to tired and we would wait till the morning. I realize he must see a doctor, we are waiting for a primary care appointment to get a primary in place and he has been using Urgent Care while waiting. With the Glioblastoma effects and his normal hard headed stubborn personality it is extremely hard to get him to participate sometimes. My question at this point is what could be the causes of a black tarry stool and a grey watery stool that would be related to each other. I understand that many things especially the treatments for the Cancer can harm the body however I am looking for something ideas that I can share with him that might assist me in getting him help. Telling him it could be internal bleeding is not enough for him as he believes the grey means it is ok and fixing. I go through this with the headaches and swelling also however since he was in a coma for 4 days and woke up after a partial resection he accomodates my requests a little better with that issue. Thank you for any advise and ideas you may give me. I am not looking for a diagnosis and realize tests have to be run for such a conclusion however help with suggestions to use in reasoning conversations would be very very much appreciated

Thank you very much. I read and research so much however sometimes as you can imagine with a person dealing with GBM explaining what I learn and why it is important to get doctors involved can be somewhat challenging.
I know the prognosis for his Cancer is bad but I see no reason to give up and let the rest of the body go through extra stresses without trying to battle them.
Thank you for assisting me in understanding how i can reason with him enough to get assistance. I very much appreciate your time and knowledge that you have given me.