Fever due to blood infection. Period?

Sir, My son(4 year old) had a fever on 11 Oct.  after taking Paracetamol, mefenamic acid the fever went away but again returned after 24 hours on 12 Oct(103°F). The blood test has following abnormalities-Neutrofil 85%, Lymphocytes 7%, monocyte 1%, WBC 20000, MCV 79.2 fl, MCH 24.5, Crp 36. Blood culture report is awaited. the doctor prescribed cefpodoxime 100 syrup. After taking 2 doses of the syrup the fever came after about 10 hours now(previously fever was coming after interval of about 6-7 hours). Does it mean that Cefpodoxime is working? If the cause of the infection was the bacteria which is not covered by Cefpodoxime then how to know it? can there be anything serious during this waiting period?