Suggest Treatment For Nausea, Headache And Altered Sense Of Smell

My husband started feeling ill on Tuesday, nauseous and really bad headache. Wednesday he felt a bit better but still a slight headache and nauseous. He smells something that no one else can smell but can t describe it. Yesterday he felt out of it , weak and chills. Today his stool is black and he s gone three times. He is feeling unwell overall.