Worried after lymph node biopsy

I went to the breast clinic after what I felt was a fullness in my breast. 
the consultant examined me and said she couldn't feel anything, I felt a bit like I was waisting her time but she sent me for an ultrasound anyway. 
went over for the scan and they found a single enlarged lymph node in my armpit, she spent a long time scanning and eventually explained that she wanted to biopsy it. The radiologist was lovely and said I'd get my results in a week but when I went back to the consultant she just said it won't be anything we'll just write to you unless it's something that needs treatment and then we'll call you. I've had no recent illness or infections. Just looking if anybody else has a single node enlarged.