Thirteen-time MLB All-Star pitcher Mariano Rivera is no stranger to pain. As an athlete, he endured plenty of wear and tear during his 19 seasons with the New York Yankees. "Back pains, knee pains, all kinds of pains," he told Fox News on Wednesday. Now, the retired pro is shifting his attention to the medical world, specifically a company that purports to be a drug-free solution to combating pain and — as a result — offsetting the use of opioids. PainShield, the signature product of NanoVibronix…