Hello - I Had A Lower Back Ache Yesterday, But

Hello - I had a lower back ache yesterday, but I had been cleaning windows. I had taken advil at 5:30 and then one Doan's pill at 10:30pm. By 11:00 I had a high fever (103) with chills that were making my teeth chatter . Took more tylenol and a cold shower around 3am. Fever broke around 5am. Back again today - up to 103 again at noon with lower back pain. More tylenol brought it down to normal, now. Just wondering what it might be. Can't find any ticks or bug bites on myself.??