Arroyo, who leads the Arizona Diamondbacks in victories, won his third consecutive game Sunday by beating the Los Angeles Dodgers, 6-3.
The right-hander induced 10 groundouts in five innings, allowed one run and five hits, and finished with one walk and one strikeout. But intense and lingering elbow pain limited Arroyo to 78 pitches.
"He's hurting," Arizona manager Kirk Gibson said. "Obviously, today you could tell. He was on reserves and using every bit of knowledge and wisdom he could to get through five innings for us.
"When he came in after the fifth inning, he said he was done. He couldn't do anymore. I'm not sure he's going to be able to make his next start."
Arroyo, 37, began experiencing elbow pain May 13, when he defeated Washington Nationals' right-hander Stephen Strasburg.
"The last four or five outings, it's just slowly sliding downhill," Arroyo said. "The last three, how I won all three, I have no idea. It's been tough the last three games not knowing if I can get back out there inning by inning."
"I've pitched through this in the past, but it's as bad as it's ever been."
The pain is eroding Arroyo's velocity, which was deteriorating before the injury.
"When I was throwing 83-87 mph, it was manageable," the 12-year veteran said. "But I'm throwing the ball 80-84 -- and 84 is when I'm sexy, you know, which is ridiculous. It's just too difficult to get big-league hitters out with that velocity time and time and time again."
Arroyo and Gibson said that the pitcher will receive an MRI soon, then discuss their next move. But Arroyo -- who won the World Series with the Boston Red Sox in 2004 -- sees the end of his career approaching with supersonic speed.
"It's just getting to the point where there's too much pain," the right-hander said. "I've got 17 more starts, or something like that, and I can't continue doing this for that long.
"I've been trying to avoid this for 20 years but I'll be facing the inevitable for the first time in two decades."