Manager Terry Francona said after Boston's 3-1 win over the Tampa Bay Rays Tuesday afternoon that Ortiz was being checked out at the hospital.
Ortiz was scratched just before the game, with Jed Lowrie inserted as DH. The original reason given for his exit from the lineup was illness, but Francona said that was a result of miscommunication.
The condition bothered Ortiz on the team's trip last week to Minnesota and Seattle, Francona said, though it didn't appear to impact his performance. Ortiz batted .500 (11-for-22) with three home runs and seven RBIs on the trip. But when discomfort persisted Tuesday morning when he ran some sprints before the game, the team decided to have him checked.
"He got an MRI," Francona said Tuesday night, "and it showed the bursitis in his heel. We're going to get him out of his spikes for a couple of days and get him into a little bit of a walking boot, just to kind of alleviate some of the pressure.
As far as how long Ortiz will be out, Francona said, "We'll keep re-evaluating him, I'm sure, every couple of days, but we want to get him off that for a little while.
"It's not going to be a DL but we're going to have to keep him out there for a little bit and we don't know what that (length of time) is."
Bursitis refers to an inflamed bursal sac, which is filled with fluid and acts to lubricate and reduce the friction between muscles and tendons. When there is bursitis in the foot, it usually occurs in the bursa sac located between the Achilles tendon and heel bone. The sac protects the tendon from the pressure of the heel bone rubbing against it.
Francona did a little lineup manipulation with Ortiz out, moving Carl Crawford up from sixth into Ortiz's fifth spot in the batting order. Jarrod Saltalamacchia moved up to sixth, Josh Reddick to seventh and shortstop Mike Aviles remained at the bottom of the order.
Ortiz also did not play in Tuesday night's game, which the Red Sox lost, 6-2.
He is batting .300 with 24 homers and 79 RBIs this season.
Information from ESPNBoston.com's Gordon Edes and Steven Krasner and The Associated Press was used in this report.