A’s Sonny Gray OK after illness, Kendall Graveman now sick

Sonny Gray was back at the Coliseum on Tuesday after a bout of what the A’s now believe to be stomach flu, and another starter, Kendall Graveman, was out with a similar ailment. Graveman is scheduled to pitch against Chicago in the final game of the series Thursday, and manager Bob Melvin said he believes Graveman will be able to make that start. With four or five team members becoming ill over the past few weeks and recent opponents, including the Giants and White Sox, dealing with the same issue, trainer Nick Paparesta addressed the team before batting practice to go over precautionary measures, including frequent hand washing. “I’ve had a Purell dispenser in here for years; now everyone doesn’t think I’m so crazy,” Melvin said. Gray said he became ill early Monday morning, and though he needed four IV bags of fluids, he did try to lobby to make his scheduled Opening Night start. “I was getting fluids and IVs, trying to get some energy and hydration back, then they told me I wouldn’t pitch,” he said. Gray had started the previous two Opening Nights for Oakland. “It was really unfortunate timing,” he said. Gray’s fiancee, Jessica Forkum, also required IV fluids, but their 1-year-old son, Gunnar, is fine, Gray said. The A’s will hold their first real “Sonny Siders” promotion Wednesday; those who bought tickets for the “Sonny Siders” section Monday still did get the T-shirt after Gray was scratched. Jason Rezaian, the Washington Post reporter held in an Iranian prison for 18 months until his release in January, is an A’s fan and threw out the first pitch Tuesday. … On Wednesday at the Coliseum, Henderson Alvarez will throw to hitters for the first time since his 2015 shoulder surgery. Alvarez, a 2014 All-Star with the Marlins, could be ready to pitch in the big leagues by mid-May. Susan Slusser is a San Francisco Chronicle staff writer.