Gaither flew to California recently to visit a back specialist to figure out why he's been dealing with back spasms and cramps for the majority of training camp.
"It's a very small tear, I don't know the medical term for it," Ravens coach John Harbaugh said Saturday. "It's not a serious thing, but it's going to keep him out for a couple weeks until it settles down because it's what's causing the spasms apparently.
"So, he's going to have to work as hard as he can and we'll have to try and work it out. I wouldn't hold my breath for about two weeks, three weeks, through camp here, and we'll see where we're at at that point."
With Gaither sidelined, the Ravens have been going with Oniel Cousins at right tackle and he's expected to start there for the rest of the preseason.
Gaither acknowledged earlier in camp that he overdid it by drastically reducing his weight to 311 pounds after playing last season at roughly 340 pounds.
The 6-foot-9 former University of Maryland lineman skipped the majority of Baltimore's offseason program.