She came to pay tribute to Janis Joplin. But despite a show-stopping rendition of Joplin's "Piece of My Heart" at the Grammy Awards on Feb. 13, Melissa Etheridge, 43, was also honoring another historic figure. Explains her partner, Tammy Lynn Michaels, with a laugh: "She's channeling Gordon from Sesame Street." But if Etheridge's baldness was a startling reminder of the breast cancer she was diagnosed with almost five months ago, her high spirits at her first public appearance since then are an indication of how well she is doing now. "I'm feeling great," Etheridge told PEOPLE. After having two lumpectomies in one breast at the end of October, she completed a two-month course of chemotherapy at the end of December. Since then, she has been undergoing radiation treatments a few times a week that will run through the end of March. The sessions have been going "just fine," says Etheridge, who decided to lop off her long locks before starting chemo, which likely would have taken her hair. Says a source close to her: "The whole family"—Michaels, 31, and Etheridge's daughter Bailey Jean, 8, and son Beckett, 6—"all helped her shave her head at home." For the Grammys, 4-carat diamond Rafinity earrings helped set off her new look. "It's kind of short," says the rock queen, chuckling, "but it is what it is."