My Left Ankle Is Swollen And Has Been For Over

My left ankle is swollen and has been for over three weeks. The ankle is also tender to the touch. I have tried icing it and that helps a little. The swelling goes down a little at night when sleeping but not completely. I went to my holistic Dr. and he didn't have a clue, but ordered a bone scan since I am 52 and have never had one. Ran into a massage therapist today, she suggested it might be a problem with lymph nodes in the foot. Would appreciate any guidance as to how to Lind out what's causing the swelling and what to do about?