Westbrook, who is recovering from Tommy John elbow ligament replacement surgery, was supposed to throw for Double-A Akron, but instead will visit Dr. Lewis Yokum as a precautionary measure to determine the extent of the arm soreness.
It has been a difficult year for Westbrook on his road to recovery. He made two rehab starts for Akron two months ago before he experienced soreness in his surgically repaired elbow. As a result, the Indians decided to shut him down entirely for two weeks.
Sunday's outing would have been Westbrook's fourth overall Minor League start this season -- and his second start in his second comeback attempt.
Westbrook last made an appearance for Akron on Aug. 4, against the Connecticut Defenders. He threw two innings, allowing two runs on four hits with two strikeouts, and he faced 10 batters in total.
He has appeared in three games this season for Double-A Akron, throwing a total of nine innings and allowing two runs with six strikeouts and one walk.
Westbrook had the surgery on his right elbow on June 12, 2008, and has yet to make an appearance since then at the big league level.
In eight seasons in an Indians uniform, Westbrook is 63-62, and he represented the Tribe as an All-Star in 2004.
Jesse Temple is an associate reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.