You may be right about the comfrey. I've read that it is an herb that has a variety of medicinal purposes. One being, the use as a compress to alleviate pain and reduce skin discoloration from bruising. It's botanical name is 'Symphytum' which comes from the Greek word for union. It was called this in reference to its use as a compress or poultice to help torn flesh heal cleanly. It has been used medicinally for the treatment of abscesses, burns, and bruises. You can obtain comfrey ointment from an herbalist.