How Can Nausea Along With Diarrhea And Low Grade Fever Be Treated?

I have had nausea, diahhrea, low grade fever, aches in lower back and back of legs, cough, mucus, headache, not interested in eating, for 5 days. Doctor put me on Tamiflu three and half days ago. Still feel sick to stomach, diahhrea even if I eat toast or banana, low grade fever, cough up mucus for 4-5 hours after I wake up. Was hospitalized 1/12/18 to 1/15/18 at Univ. Of Penna for pneumonia and Atelectics and lung impactions of mucus showed up on CATSCAN. They sent me home after 3 days because I have Common Varriable Immune Disease and the we’re affraid I would catch something else in there. Have had visiting nurse, aides, and therapist at home. I am 71 and have had Chronic Asthma/Chronic Bronchitis since 5/1992. Lungs damaged from my Job working for TRANE HVAC as a replacement Coil Specialist. Never smoked. I don’t know if this is the Flu or something else. Need another opinion.