Throbbing pain getting on your nerves? Some 120 million to 130 million Americans — nearly half of US adults — are believed to take an over-the-counter pain reliever at least once a week. Gen Xers, born between 1965 and 1980, use them most frequently . But they don’t always find relief. That may be because they’re taking the wrong tablet for their aches or they’ve built up tolerance to the medicine. It’s possible they shouldn’t be consuming pain relievers at all — people with liver disease,