Hi ! The sudden onset of severe thigh pain with a hard knot like swelling in the upper thigh area in a person with a history of COPD
, may signify a femoral hernia
though less frequent in males. However, I would suggest you to take your Dad to your family physician or a surgeon, as it may not be possible to give further opinion on this without your father being clinically examined by a doctor. Wishing your dad an early recovery.