After retiring from playing professionally, he has coached high school and youth soccer for over twenty years.
After graduating from high school, he attended Southern Illinois University Edwardsville where he played on the men's soccer team from 1973 to 1976.
He is ranked ninth on the school's career scoring list with twenty-seven goals and twenty-two assists.
On June 13, 1982, the Roughnecks traded Twellman and John Tyma to the Chicago Sting in exchange for Tasso Koutsoukos.
On March 21, 1982, Twellman earned his only cap with the U.S. national team as a defender in a 2–1 win over Trinidad and Tobago.