SEATTLE (AP) - After nearly two weeks of cramping and vomiting, a Mountlake Terrace teenager finally learned what caused his illness: swallowing a bristle from a wire grill brush. Sixteen-year-old Tristin Beck tells The Seattle Times he must have swallowed the bristle when he ate a piece of chicken during a barbecue. His mom says that as his symptoms worsened, doctors at Seattle Children's hospital ran "about a million tests." Finally, on Sunday night, they performed an exploratory surgery and found the tiny strand of wire stuck inside Beck's small intestine. Beck is expected to make a full recovery. Experts say such cases occur more often than people might think. One was in Washington last July, when Tacoma's Adam Wojtanowicz underwent emergency surgery because of a brush bristle.