12 days fever calls for some investigations. Please get CBC including platelet count & test for MP, a Widal Test for Enteric Fever Typhoid, IgM Dengue & Chikungynya, a Urine test for pus cells (If you get urine test while taking Antibiotic, it may not come positive. If there is any complaint other than what you have already mentioned, must be told to your doctor eg cough, throat pain, fever with chills/rigors, burning of urine, diarrohea etc.
Next Steps
Must consult an Internal Medicine Physician.
Health Tips
Eat well. drink plenty of water, juices & soups, record your fever during the day 3-4 times to see the type of fever and show it to your doctor