My mother's maiden name was also Ewert. Her family came to Canada from Estonia in the early 20th century. I am reliably told that the name is northern English, possibly a sept of clan Macfarlane, originally from 15th or 16th century Roxburghshire, and the name may have a similar meaning to shepherd. "Ewe herd" sounds to me like a specialist, possibly a vererinarian. My mother's mother came from one of the larger islands of Estonia and her family were serfs of a baron.