<s>[INST] I think while working out or stretching i may have tweaked a vein or tendon under my arm. Theres a small round ball in yhe middle and shen my arm is against the wall while looking in mirror, vein or whstever is more pronounced . Hurts ehen i pudh on it [/INST] Hi, dairy have gone through your question. I can understand your concern. You may have enlarged axillary lymph node due to reactive hyperplasia or lipoma or some cyst.  You should go for fine needle aspiration cytology or biopsy of that lump. It will give you exact diagnosis. Then you should take treatment accordingly. Hope I have answered your question, if you have doubt then I will be happy to answer. Thanks for using Chat Doctor. Wish you a very good health. </s>