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For low hemoglobin further workup needed in form of peripheral smear examination, serum ferritin estimation, and serum TIBC (total iron binding capacity) estimation to classify your anemia. ESR (erythrocyte sedimentation rate) can be high because of any non-specific inflammation or infection like condition. It indicates some pathology is there but do not give an exact diagnosis.
You are losing weight hence history should be taken regarding a cough and chest X-ray done to look for any respiratory pathology of present especially tuberculosis. Second, if suspected then rule out HIV by ELISA fourth generation. Sometimes, over-exertion and less nutrition or prolonged fasting also can lead to weight loss. But as you are having on and off fever I will advise you to consult a physician for your physical examination including liver, spleen and lymph nodes palpation. If a specific cause is found, then treated accordingly.
For more information consult a hematologist online --> https://www.icliniq.com/ask-a-doctor-online/hematologist