Shall I take injectable vitamin B12 to improve my fatigue symptoms?

Hi doctor,

I have been diagnosed with chronic fatigue syndrome. I am taking 0.11 oz of Valtrex a day, which increased from 0.07 oz for four months. Until a month ago, my CFS seemed to be improved. Then last month, I had a major setback with the return of symptoms beyond fatigue, such as heart palpitations, tinnitus, tingling or burning in hands and feet, balance problems, shortness of breath, loss of appetite, and a new set of stomach pains with occasional diarrhea. I am taking B12 and folic acid orally and my last B12 test was high. I think 1600. My blood work has been borderline pretty consistent for years and it is followed by the most recent CBC, which was taken last month and is as follows. HCT around 37, 35.7; HGB around 12, 12.6; MCH around 34, 36.5; MCHC around 32.5, 35.2; MCV around 101, 103.9; platelets 146 to 119, 152; RBC around 3.6, 3.44 and WBC around 4.2, 4.5.

My doctor has told me that these results are not significant and cannot be an explanation for my recent major relapse. I read a recent case report where the B12 blood test does not always mean that the B12 is being absorbed or used by the body. Is there any possibility that this minor turndown could be responsible for symptoms? Is there any downside to start injectable B12 to see if it makes a difference? Are there any additional blood tests that might clarify this? I know that the dosage of Valtrex is high and that antiviral can affect CBC.