SAN ANTONIO, Texas – Since Thanksgiving, PGA Championship winner Jimmy Walker has battled fatigue. He’s suffered a loss of strength. And his normal happy disposition has given way to bad moods and irritability. On Wednesday, he revealed why. He’s suffering from Lyme disease. Tests taken the Wednesday of Masters week came back positive for the disease, a bacterial infection that infects approximately 300,000 people each year in the United States. Walker thought a couple of weeks ago that he had mononucleosis, but further results confirmed the Lyme disease diagnosis. “We’ve been talking to a lot of doctors,” Walker said on the eve of this week’s Valero Texas Open, an event he won two years ago.