Continous high fever. Makes him strong

Hello doctor my uncle 48 years old. Recently he suffer with urinary infection. After the treatment He suffer with both malaria and typhoid . He joined in hosptal they are advice full body check up.  In All reports every thing is normal doctor said that nothing to worry. But fever comes and go 100-103 rangeseverytime and his tongue is completely bitter in taste unble to eat anything he is very suffer with this. During typhoid fever he tested diabetic also.. CT scan also done every thing normal. Except fever  there is no symptoms. He is done covid test and RTPCR test also  he tested Negative But what is the reason sir please help me .. He is mentally disturb with his health condition. He suffer since last 4 months with illness. Your suggestion makes him strong 🙏