What Causes High Fever, Severe Chills, Fatigue And Some Headache?

I just recovered from several days of high fever and severe chills with fatigue and some headache. Since I had lithotripsy several days earlier and was being treated for an unresolved UTI, I suspected a kidney infection and so did my urologist. I received IV antibiotics (and a ureteral stent). Unfortunately, now both a friend and my husband have what appears to be the same chills, fever and fatigue. No respiratory symptoms, no muscle aches, no GI symptoms. Can t sort out what it might be.