Fever and mild chills. How to proceed.

I am having fever and mild shivering on and off for about 12 days with little body weakness. I don't feel feel these symptoms all the day. Usually during the nights i feel slight shivering. The normal temperatures when i feel fine is in the range 98.2 F to 98.6 F. But when I feel the shivering and fever sensation the temperature is the range 96.8 F to 97.1 F I consulted a doctor and did some tests like CBP, CRP, typhoid test, malaria, dengue, covid rtpcr test. All came negative and values are within normal range. My doctor suggested monocef cv and some vitamin supplements. And i have no medical history of diabetes, BP, asthma etc. I don't have any other symptoms. No cough, no cold or any pains except fever sensation and mild weakness at some time during the day. I don't know how to proceed.