Last Year I Had An Axillary Lymph Node Suddenly Swell

Last year I had an axillary lymph node suddenly swell up to the size of a chicken egg. mAy doctor prescribed Cipro for 10 days and the node decreased in size by more than half in about two weeks. It continued to decrease in size after the antibiotic was finished but at a slower rate. I finally decreased to the size I could no longer find it with my fingers. About 3 weeks ago, it enlarged again but to only about half the original size and within 2 weeks it began to decrease in size again without any treatment. It remains today at about the size of a grape but seems to be decreasing. It has always been slightly tender to the touch. At the time the lymph node re-appeared 3 weeks ago, I felt terrible for about 2 days. just exhausted feeling with no energy, but no pain. I am unaware whether I had fever or not. I did not feel like I had a temp. Why would a node swell up huge like that, go away and come back again?