I Have Had Diarrhea For 3 Days Now And Have

I have had diarrhea for 3 days now and have developed a sore throat and cold ... Are these symptoms of the flu? The reason I am so concerned is that I am currently taking care of my brother (away from home) who has throat cancer and was given 2-3 weeks to live in April ... He has no roof to his mouth and the cancer is in his cheeks, sinuses, etc.
one of the head nurses suggested that EVERYONE get a flu shot, which I Have not done as of yet. I don't know if I should go to Urgent Care for treatment, as this is the last thing he needs with his sinuses draining down the back of his throat now anway. I can't imagine how this would affect him.
Any suggestions?