Young, who has been hit hard in his last four starts, had an MRI exam taken of his right shoulder after his last start on Sunday. He said the test did not show any structural damage.
"There is inflammation or a strain in there that's going to take a little bit of time," Young said. "It's something I've been fighting the last four starts and it's progressively got worse each time. It's now at the point where it's not recovering between starts."
Young was scheduled to start at home on Friday against Oakland but will miss that start. He said he's not sure when he will make his next start.
Young has lost each of his last three starts, including last week at the Los Angeles Dodgers when he allowed four home runs. On Sunday, he gave up five runs on four hits in 2 1/3 innings of a 6-0 loss at the Los Angeles Angels of Anaheim.
Young is 4-6 with a 5.21 ERA in 14 starts.
In another move, former Padres right-handed pitcher Brian Lawrence was signed to a minor league contract on Tuesday and will make his first start with Triple-A Portland Wednesday. Lawrence previously pitched for San Diego from 2001-05 and won a career-high 15 games in 2004.
The club placed right-handed pitcher Luke Gregerson on the 15-day disabled list, retroactive to June 8, with a strained right shoulder, and transferred right-handed pitcher Shawn Hill to the 60-day disabled list. Hill was originally placed on the 15-day DL on April 26 with inflammation of the right elbow.