Joint swelling - elbow

I had chemo and radiotherapy following breast cancer lumpectomy ( non lymph nodes affected but 13 were removed).

About 10 days after radiotherapy finished I did a littel swimming - not much - and afterwards there was a littel pain and some swelling ( round like  a walnut) in the crick of my arm. It hasn't gone down ( although it was never very big). The pain has gone.

Is this lymphedema starting? Should I worry?  Should I stop taking any exercise ? My doctor seems unconcerned but ny granny had lyphedema so I do worry?
Many thanks

[CCF-RN,MSN-JS]

Dear Jemina, Lymphedema is an abnormal build-up of fluid that causes swelling in the arm.  Lymphedema can develop when lymph nodes are removed.   It is a difficult condition to treat once it develops so prevention is the key.  

Lymphedema is usually more of a generalized swelling in the arm, so I'm not sure that what you are describing is related to lymphedema.

For more comprehensive information about lymphedema prevention and treatment we have information on our Cleveland Clinic Website. Which is www.clevelandclinic.org once there, click on Health Information Center, then type in lymphedema.