"The doctor might say, 'Don't pick up the ball,'" Riggleman said. "The doctor might say, 'Hey, this looks fine.' This is typical pitching stuff, go get 'em. But I doubt it."
Rizzo called any reports that the Nationals had already decided to shut down Strasburg for the season "inaccurate." The GM said Strasburg told him he had this type of injury in college and pitched through it.
Strasburg changed into street clothes before Sunday's game and left for his exam in Washington without talking to reporters.
He's 5-3 with a 2.91 ERA and 92 strikeouts in 68 innings.
"I think he's a little dispirited right now," Riggleman said.
Strasburg was making his third start since returning from a stint on the disabled list with inflammation in the back of his right shoulder.
He grimaced and shook his right arm after a pitch to Dominic Brown and was removed without any warmup tosses
Strasburg was in control until he got hurt, striking out six in 4 1/3 innings while allowing two hits and a run.
The Nationals will surely be cautious with Strasburg. The No. 1 overall pick in the 2009 draft, he was scratched minutes before his scheduled start against Atlanta on July 28 and was diagnosed with inflammation in his right shoulder. He was placed on the 15-day disabled list the next day.
"The fact that it's not in the same place as the last one might indicate, hopefully, that it's not some chronic thing in one part of his arm," Riggleman said.