There are a lot of great ideas here! I would like to add one more. Because you have had a lymph node dissection, you do have a higher risk for local inflammation under your arm. I now get a sore inflamed lymph node under my arm every time I have a little allergy. I also get a little lymphedema pretty often.
Is this tenderness constant or does it come and go? Is there swelling? Final question, lol, does anything make it better?