Hi, Thanks for writing in. A swollen lump in the armpit is most likely a lymph node swelling. It is not significantly related to high protein diet or intake of caffeine. If you are having a painful and tender lump showing signs of inflammation then it is probably due to an acute infection. This is usually treated with a short course of antibiotics. Should it be painless and firm lump then it might be a concern. This might require you to see your surgeon and get a detailed medical examination done including blood tests, imaging investigations and biopsy from the lump to correctly identify the condition. I suggest you to please consult your surgeon immediately and have yourself examined. Your doctor might suggest an ultrasound scan of the lump if required. Should you have any more similar lumps anywhere else in your body then your doctor must know about it.