Pain in the armpits, lower neck and back is often caused by swollen lymph nodes and can be treated with over-the-counter medications such as Advil, Motrin, Aleve or Tylenol, according to WebMD. Applying warmth to the area with a wet washcloth and getting plenty of rest may help.
Swollen lymph nodes often indicate an underlying illness or infection, states WebMD. They may swell to two to three times their normal size and form a very tender lump. Individuals with swollen lymph nodes accompanied by high fever, discoloration of the skin, difficulty breathing or swallowing, weight loss or excessive sweating while asleep should contact a medical professional to help diagnose and treat the underlying cause.