Fever up to 40 degrees fir 72 hours reaccuring every 3-4 weeks with no other symptoms in a 5 year old. what can be the cause?

Evaluation: Recurring elevation of temperature readings usually indicates an infection which is untreated. Other possible causes include malignancy, autoimmune disease. The presence of additional symptoms including rash, cough, GI symptoms should be communicated to your PCP right away. Evaluation should include CBC, differential, platelets, ESR, CRP ,PCR SarsCoV-2 and cultures, including a urine culture.