Neck on r/side keeps swelling up, Mri showed an inlarged lymph node, all other scans were normal, had for 3 months now. .. What could it be?

If you have. persistent swollen lymph nodes on one side of your neck only , chances are its from an infection ( skin most likely source ESPECIALLY THE SCALP!!)) If this persists without a defined source lymph node biopsy might be the next step! Discuss this in detail with your Primary Care Physician! Hope this helps! Dr Z.