CBC Shows Low Monocyte Count And High BUN, Persisting Weakness With Vitamin B Injection And Pills. Could It Be Other Than B12 Deficiency?

Hi, blood work normal (CBC) except low monocyte count and BUN a little bit high. Symptoms: Quite severe weakness in the morning, gradually better during the day and the evening. Pale face and some tingling in the forearms but not much lately. No stomach problems, no bowel problems, urine seems ok and stools also normal. I have not seen any blood in it. Doctor gave Xanex and B-vitamin pills two weeks ago and I have been taking now B-vitamin injections (complex) and I bought today also B12 vitamin injections, in case of not good absorption in the stomach (I have been using antacids quite often during recent years). Those seem to help somewhat but still quite weak. What else this could be then simple B12 vitamin deficiency?