What would cause prolonged fever and low platelet count? I have had a fever for 10 days, max temp on average 101.5 at night. I swear profusely in the morning as it breaks and then am afebrile until the evening brings another round. I have also experienced significant headaches with some neck pain, though not typical meningitis type neck pain. More like a bad crick on the right lower skull and the pain expands from there. No other symptoms except intermittent flank pain. I had a UA done to rule out pyelonephritis. It was negative except for large blood, so I was diagnosed with viral infection and kidney stone. Strep and flu A/B were also done and negative. I then had a CBC and CMP done. CMP was unremarkable. CBC showed normal WBC at 7 and low platelets at 136 with possible enlarged platelets on the smear. I am so tired if being sick. Is there anything else I should have checked?