Schelin grew up in Kållered outside Gothenburg and began to play football for Kållereds SK along with her sister, Camilla. She has also played for Mölnlycke IF. Schelin was also adept at such sports as table-tennis, track and field, and snowboarding before opting to focus on football full-time. As a teenager, she developed problems with her spine and was advised to stop playing the sport. Schelin went through intensive strength training and recovered by the time she turned 17.
In 2001, when she was 17 years old, Schelin made her debut in the Damallsvenskan for Landvetter FC, now known as Göteborg FC. She played in over 100 league matches with the club establishing herself as one of the club's most prominent players. After an injury in August 2002, she was out of the league for almost a year and a half returning in June 2003. In 2004 Schelin was named Breakthrough Player of the Year after netting 14 goals in 15 games for Göteborg FC.
In 2006, Schelin was a key player in the 2006 edition of the Algarve Cup; leading Sweden to a respectable third-place finish. She scored the only goal in the bronze medal victory over France. For her efforts, Schelin was awarded the Diamond Ball as the country's best female football player. That same year, she was named the Forward of the Year in the Damallsvenskan. Schelin's success made her a huge face in her country and she was rewarded when she was selected to attend the 2007 FIFA Women's World Cup draw in China on behalf of Sweden.