Armpit pain

I had breast cancer three years ago on my left side had mastecomy and now on tamoxifen.  I have been noticing for the last couple of months that on my right side upper outer part of breast and into armpit area it has been aching.  My armpit area in that location is very lumpy, so do not really know if there are any lymph nodes enlarged.  Two questions:  Is is normal to have an ache that comes and goes for a couple of months in the armpit / breast area AND what does an enlarged lymph node feel like?  How big are they (size of pea or do they need to be larger to be enlarged?)

[CCF-RN,MSN-rf]

Dear Pattsy:  Pain in the breast is not uncommon and there are many possible explanations.  Lymph nodes can vary somewhat in size based on the location and the situation.  Lymph nodes may be considered enlarged when they are larger than 1 centimeter (about 1/2 inch).  If you are feeling lumps and are concerned, you should be examined by a physician.