Aretha Franklin: Side effects of treatment "were rough"

Aretha Franklin says "the side effects were rough" from her treatment for an undisclosed condition.

The 71-year-old singer sat at a piano Wednesday inside a Westin hotel in the Detroit suburb of Southfield. She sang Etta James' "At Last" and told reporters she's "glad to be back in it" -- a reference to her music.

The Detroit News reports she's starting on a new album with producers Kenny "Babyface" Edmonds and Don Was.

Franklin says she and Edmonds were supposed to team up in July, but couldn't because of her medical treatments. She says it was music executive Clive Davis who suggested she collaborate with Was, known for his work with the Rolling Stones, Bonnie Raitt and Willie Nelson.

A new album has been in the works for a while. Back in April 2012, Franklin told CBSNews.com that she had been eyeing new music, saying, "We've got the hottest new producers coming in writing, and it's going to be better than it's ever been."

Franklin canceled several concerts earlier this year for health reasons.