Puka Nacua is getting help this offseason -- the Los Angeles Rams superstar checked into rehab to focus on "personal growth" early last month ... weeks before a woman accused him of biting her during a New Year's Eve outing. Levi McCathern , Nacua's attorney, tells TMZ Sports Puka's currently at a state-of-the-art holistic care facility in Malibu ... and he's using the time to get in tip-top shape personally and professionally ahead of the season. McCathern said Nacua will be out in "plenty of