What could cause sore head, neck, armpit glands 2 months, high absolute & % lymphocytes, abn protein band ("poss monoclonal protein"), high phosphorus?

Variety of causes: The constellation of findings you report can be due to a variety of causes and it would be important to have all of the clinical details available to formulate a differential diagnosis. It sounds like you are being seen by a health care provider. Would recommend seeking clarity from that provider or a second opinion if you don't feel your questions are being answered.