Britney Spears reportedly checked into an exclusive spa “for some R&R” — and some are wondering if the a third “R” — rehab — is in store … “With these celebrities, ‘exhaustion’ sometimes means something else and a little rest at a spa sometimes actually translates into something a little more serious,” says a source. Spears’ rep couldn’t be reached for comment, but L&S reports that the singer’s parents are urging their daughter to go into therapy. “It’s just been heartbreaking for her parents to watch Britney on this downward spiral,” an “insider” told the mag. “It’s so sad.” according to MSNBC.