If the swelling appeared suddenly and it is painful, tender to touch and doesn't feel hard, there is no need for worry.
Swollen lymph node due to infection will disappear within two weeks.
Swollen lymph node that is hard and not painful, doesn't easily move under skin, can indicate something more serious like breast cancer (breast cancer can affect the lymph nodes under armpit before the breast tissue itself).
Another symptoms you are experiencing are most likely due to asthma.