A 47-year-old patient is suffering from relapsing fever. His investigations regarding Typhidot, Lipid Profile,LFT's, RFT;s, CBC are normal. His ESR is 30. Blood culture shows no sensitivity.

Medication: Levocetirizine 5mg (Occasional), Tab. Citalopram for the last 4 years. What should be ruled out? Suggest any specific cause.