Worried about swollen painful lymph nodes in left armpit

I am 64. Earlier this summer I went for a calcium scan of my heart. That came back excellent but it showed swollen lymph node under my left armpit. I do breast exams but didn't notice this. I was sent for an ultrasound of both breasts, my nodes and a mammogram (which I always have done once a year). It came back negative. Fatty breasts. non cancerous. Unfortunately I now have pain for the last couple of months and the pain is getting worse. I feel pain into my lower left breast now too. Today my neck and shoulder hurt. I am taking advil but I am still in pain. I am scheduled for a chest MRI  with concentration on the left side in 12 days. I am also caring for my husband, 69, a Viet Nam marine vet with cancer. I am anxious and worried as I need to be healthy to care for him. Trying to find time to care for him, take care of everything and then find time for me has been difficult. I retired from my job because I can't do it all anymore.  Thanks for listening.