Romero lasted just one-third of an inning in Wednesday night's 10-4 loss at Tampa Bay, the shortest start of his career and the quickest exit by a Toronto pitcher since Esteban Loaiza got only one out on July 2, 2001.
Romero, who gave up three run-scoring singles, lost his rotation spot after a poor spring training and remained in Florida to work on mechanics. He was called up May 4 when right-hander Josh Johnson went on the 15-day disabled list.
Romero is 0-2 this season with a 12.46 ERA.
Toronto filled the roster spots by selecting the contracts of right-handers Ramon Ortiz and Mickey Storey from the Bisons. Ortiz was 2-0 with a 2.18 ERA in four appearances with Buffalo, while Storey went 0-1 with a 3.93 ERA in nine relief appearances at Triple-A.