Noticed some slight swelling left armpit (near the muscle area & pitted area) and experienced pain at the armpit and also pain on the upper arm. Occasionally I m also having backpain . Not sure the swelling is the swelling of the lymph nodes??. The pain from my armpit can sometimes radiatate to my left breast. I have breast cyst at left breast (2 o clock) with size of 3.66mm and fibroadenomas at right breast as well. Due to my endo and heavy menses, I ve been taking Yaz oral contraceptive pills and have Mirena IUD to control my heavy bleeding for the last 2 years. Just done my breast Ultrascan today and result shown no mass on the armpit nor any suspicious looking cyst at the breast. My doctor mentioned that the pain I experienced could be due to hormones and also due to nerves and muscle pain. My doctor also mentioned that it is not necessary armpit of both arms must be the same size. Is this true?? Actually did a mammagram 6 months before but breast is too dense to see . Doctor only prescribed me with Neurobion . Hope to have some doctor s advice here. Thank you. Sasha