"It's definitely a mental blow," Jackson said. "It's borderline embarrassing, just because I come over to a new organization and I've only played  games. I know that they had high regards for me coming over here and I felt like health has ridden my performance. It's just frustrating, that's not even the word I'm looking for."
Jackson said he's felt discomfort in his lower abdomen and groin since March and that he hoped to play through the pain this season. But during his first at-bat of Thursday's 4-3 win over the Rays, Jackson said he aggravated the injury and that he could barely get out of bed on Friday.
Jackson has seen three or four doctors regarding the injury dating back to his time with the D-backs earlier this season, but the A's hadn't yet diagnosed the injury before Friday's game.
Jackson said surgery is "the route we're looking at" and that recovery time for such a surgery usually runs four to six weeks. The A's have roughly six weeks remaining in the season. Jackson said he will meet Philadelphia-based Dr. William Meyers, who is renowned for diagnosing sports hernias, on Sunday.
"It's just hard to come in here and face your teammates and not be able to go out on the field and play with them," Jackson said. "I grew up a baseball player and it's tough watching. ... You've got to draw the line somewhere."
Jackson said teammate Travis Buck underwent a similar surgical procedure and that Buck was out for four to six weeks.
Jackson has missed 55 games this season due to a strained right hamstring, 37 with Oakland and 18 with Arizona. He said he believes his current abdominal injury may have led to his hamstring strains.
"Luck has not been on his side this year," manager Bob Geren said. "I feel bad for him because he's such a good player, but hopefully he'll be back there soon."
With Larish, the A's get a player who can play first and third base. It also means top power-hitting prospect Chris Carter will remain in Sacramento for the time being.