Have had swollen lump nodes in neck and behind ears, under left arm and left elbow for a month now. What should I do and what could it be?

See MD. Swelling of lymph nodes as you are describing requires a medical evaluation. Nodes in more than one place may be a viral infection, but this could also represent a more concerning diagnosis, as a possible malignancy. Please see your doctor this week and make sure you keep a record of othe symptoms and fevers or weight changes. Good luck.