Lumps under skin. Could be lipomas (fatty growths), cysts, lymph node enlargement or even skin cancer. See a dermatologist and have it checked out.
Axillary lumps. Lumps in your axillary (arm pit) areas can be axillary abscesses, infected hair follicles (especially if shaving, etc.), possible inflamed lymph nodes, etc....So it is best to get an evaluation to get the proper diagnoses, so your painful lumps can be treated appropriately. Best wishes.
Need to examine. It is not feasible to provide a meaningful opinion without examining you and your symptoms warrant evaluation by a physician.
Probably lymph gland. More likely you have infected lymph glands. See your doctor for proper diagnosis and treatment. Left untreated, these may develop into open sores.
Have it examined. Most likely it is either infection of the sweat glands or inflammation of the lymph gland. See your md and have it examined and treated. Antibiotic may likely be needed. Good luck.