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Based on your query, my opinion is as follows:
The elevated hemoglobin, red blood cell count and hematocrit signify polycythemia. Elevated Vitamin B12 level is one of the markers of myeloproliferative disorder. I would strongly think of polycythemia vera.
Other values are within normal range (attachment removed to protect patient identity) suggest no renal or liver disorders.
Increased hematocrit will slow down blood flow due to increased viscosity and this can cause few RBC to move out and lead to these symptoms. Even migraine, bone pain and increased itching can be attributed to sluggish blood flow.
Polycythemia vera is a cancerous condition and requires evaluation. I would strongly urge you to meet hematologist.
Hope there are no other causes of polycythemia like lung disorders or staying in hilly regions, etc.
With high vitamin B12 and polycythemia, polycythemia vera needs to be seriously evaluated.
For further information consult a hematologist online --> https://www.icliniq.com/ask-a-doctor-online/hematologist