Hi welcome to the health care magic You are having evening fever and malaria report negative ESR elevated in any inflammation, viral infections , bacterial infection etc... It is non specific marker and not sole marker of infection Provide me your CBC report.. If high count and neutrophilia present then chance of bacterial infection high... Your other complaints should be elicited like cough, sore throat, abdominal pain etc to reach up to exact foci of infection If infection suspected with further investigation and by examination then broad spectrum antibiotic course can be prescribed for five days Hope your concern solved Consult physician for examination and discuss all these with him Take care