April 17 (three days before Hays hurt his leg):
"Austin Hays doesn’t want to say the first two weeks of the regular season were like spring training to him.
"He knows those games mattered. But he entered the season cold at the plate after dealing with a stomach virus that saw him lose 10 pounds. He was absent from spring training for four days, then spent the next few days trying to rehydrate and feed himself. It took him nearly a week to return to just hitting again and, after getting hit in the shoulder during his first spring training game back, a full two weeks just to start to feel like himself again.
"Hays got sick again in Pittsburgh during the first weekend of April. He’s just now back to the weight and strength he had before the illnesses, he said, and finally feeling healthy enough to contribute."
Orioles’ Austin Hays, after losing 10 pounds due to sickness, finally feels back on track - The Baltimore Banner
It's also been mentioned in Roch's blog several times.