My aunt and mother had this too, and there is a syndrome (that neither can remember the name of) that this is the main symptom of.  (They found the name on the internet) It eventually went away for them...  Also, lower leg swelling is sometimes related to a weakness of kidney function.  An idea might be to find a practitioner who uses the SCIO biofeedback device, which detects stress in the system and can also give therapy.  Using this device, I've had phenomenal results for swelling....