The injury means that, if Carson Wentz is unable to play in time following foot surgery earlier this month, Jacob Eason would be the Colts' starter for their Sept. 12 regular-season opener against the Seattle Seahawks.
Wentz returned to practice Monday and said he was "optimistic" about playing against the Seahawks.
"It didn't look good," Colts coach Frank Reich said of Ehlinger's injury after the game. "We need to wait for the doctors' final say."
Ehlinger will recover without any medical procedures, the source told Schefter.
Reich said last week that he would like for Wentz to have at least two weeks of practice before playing in a regular-season game. He could have almost three weeks of practice before facing the Seahawks as long he doesn't suffer any setbacks. The original timeline for Wentz's recovery was five to 12 weeks.
Information from ESPN's Mike Wells and The Associated Press was used in this report.