"It feels better than yesterday," Hardy told reporters Monday, according to MASNSports.com. "It's still a little bit tight, but it's definitely getting better. We'll see. I'm basically through my first round of treatments today. I'll probably do the same thing again and go from there."
Hardy said he's unsure if he'll be able to return Tuesday.
It is not the first time that Hardy has been plagued by back spasms as he missed two games during the 2013 season when he hit 25 home runs with 76 RBIs for the O's.
"Very, very frustrating," Hardy told reporters. "It was probably the healthiest spring training I've had yet with everything feeling good, and then this came out of nowhere."
Hardy said his back tightened up again while taking ground balls before Sunday's game against the Detroit Tigers.
"We just want it resolved now," Orioles manager Buck Showalter told reporters, according to MASNSports.com. "Lot of guys have stuff that they play with that we don't make note of, but this one just hampers him."