The Seattle Mariners are putting left-handed pitcher James Paxton back on the shelf after an MRI revealed inflammation in his throwing shoulder.

Paxton will do no throwing activities until the inflammation dissipates, which is expected to take at least five-to-seven days.

The announcement came three days after Paxton threw 62 pitches in a rehab start for Triple-A Tacoma, which marked his first game action since suffering a strained back muscle in an April 8 start against the Angels.

The news represents something of a surprise. Paxton reported some minor soreness in his triceps after Saturday’s game.

The Mariners also reported right-hander Stephen Pryor will be placed on the seven-day disabled list for minor-league players after being diagnosed with a shoulder impingement.

Pryor is recovering from a torn back muscle that sidelined him for nearly all of last season. He has allowed 16 runs and 20 hits in 18 innings between Tacoma and Double-A Jackson this season in 16 appearances with 16 walks and 13 strikeouts.

Club officials said Pryor is likely to miss at least a week.