A haematoma is a collection of blood, that usually occurs in soft tissues such as muscle, and tends to occur after injury. A large haematoma can cause the symptoms that you have. If the symptoms persist, surgical drainage of the haematoma is often required. Whether you need it or not is difficult to say, without examining you. Individual opinions may differ, but I think your doctor is probably correct in advising drainage. Appropriate doctor: cannot advise; Appropriate hospital: depends where you live.