Sheffield received a second shot in his right shoulder on Wednesday after getting one in each shoulder earlier this week. This one was more focused on the spot where he had labrum tears surgically repaired last fall.
He's hoping this shot finally allows him to swing a bat pain-free and return to the Tigers lineup, possibly by Friday, but the lack of progress is enough that he's considering the worst-case scenarios.
"I'm doing what I need to do to get it strong," Sheffield said on Thursday morning. "If it hurts, I have to let people know it hurts. I can't continue to go out there and play like that."
Thursday marked Sheffield's fifth consecutive game out of the lineup, but he has been dealing with shoulder issues pretty much since returning to action in Spring Training. He visited earlier this week with team physician Dr. Stephen Lemos, who found no structural damage, and he underwent cortisone shots in each shoulder to alleviate the soreness.
The shot in his right shoulder had little effect. Sheffield said he still felt pain even without doing baseball activities. Simply crossing his arms, he said, he could feel it.
It's enough of a concern now that Sheffield said he and team medical officials have contacted Dr. John Uribe, the surgeon who repaired his labrum last October, to get his take on the matter and make sure there isn't something worse to worry about.
If it becomes a longer-term issue, Sheffield said, then the end of his career becomes a consideration.
"Am I wasting my time trying to play? That's another thing," Sheffield said. "I might have to make a decision again. I'm not going to put myself through [more surgeries and rehabs] like the past. I'm not going to do that. I don't need to play. It's just a matter of having an opportunity to win again. That's the only reason I'm here."
Asked if he's thinking about retirement, Sheffield said, "I've been thinking about that for four years, but it just doesn't seem to happen. I can't really think emotionally about it. I have to think it all the way through, and I don't think I've done that yet."
Jason Beck is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.