Dr put me on doxycyl 100mg for rickettsia, tick bite fever. i have bad fevers and chills. my body is aching everywhere as if i have the flu and my eyesight is blurry, i have started having diarrhoea too.i am only on my 3rd dose, should i be worried?

Contact doctor ASAP: Tick borne relapsing fever is not a rickettsial disease, but due to a bacteria called Borrelia. Sometimes TBRF treatment causes a Jarish-Herxheimer reaction when the antibiotic rapidly kills billions of bacteria releasing toxins into the blood, with high fever, chills etc for 1-2 days. If blurry vision means brain involvement, you'll need IV antibiotic. Immediately contact the doctor treating you.