Oakland right-hander Sonny Gray can’t figure out what’s going wrong.

Gray was knocked during Boston’s six-run fourth inning that carried the Red Sox to a 14-7 victory over the struggling Athletics on Monday night.

It was Gray’s third straight poor start. He’s given up 18 runs in 12 2/3 innings.

“I’ve had some, a bad game, two bad games, but this is kind of three in a row now that’s not just been pretty pathetic, but they’ve been very bad,” he said. “It’s definitely a struggle and I’m going to have to start getting some people out here soon.”

Khris Davis hit his seventh homer and drove in two runs for Oakland, which has lost 12 of 16 and fell to 1-7 this month.

Josh Reddick’s club-record streak of hits in eight consecutive at-bats was stopped when he grounded out his first time up.

But it’s Gray’s unusual stretch of starts that has Oakland concerned.

“Yeah, that’s the hard part when a guy’s been as good as he has been and as consistent as he’s been to go through a struggle,” Oakland manager Bob Melvin said. “It’s foreign territory for him.”

Gray gave up seven runs and eight hits in 3 2/3 innings. He is 1-3 with a 9.61 ERA in his last four starts.

Jackie Bradley Jr. extended his career-high hitting streak to 15 games with a two-run single in the big fourth and added a grand slam two innings later, carrying Boston to its seventh win in 10 games.

Brock Holt hit a two-run homer, and David Ortiz had three hits and two RBIs for the Red Sox.

Clay Buchholz (2-3) gave up four runs and six hits in five innings.

Oakland scored in each of the first three innings to open a 4-1 lead before the Red Sox charged ahead with their six-run inning.

Boston chased Gray (3-4) during an inning in which the Red Sox had seven hits, two of them doubles off the Green Monster by Ortiz, and sent 11 batters to the plate.

Travis Shaw’s RBI double and Bradley Jr’s single tied it, and Mookie Betts doubled in the go-ahead run. Dustin Pedroia’s run-scoring single made it 6-4, and Ortiz capped the rally with an RBI double against Fernando Rodriguez.

Holt homered in Oakland’s bullpen the next inning, and Bradley hit his slam over a short wall in deep right.

Davis’ homer landed into the first row of Monster seats.

Notes — LHP David Price (4-1, 6.75 ERA) had a bullpen session, hoping to correct his delivery after a rough start this season. “The focus – in addition to his normal work routine – was to try and get him to stay over the rubber a little longer and get his hands separating a little bit more in sync with his normal delivery,” manager John Farrell said. … RHP Sean O’Sullivan (0-0, 0.00 ERA) is slated to make his first start in a Red Sox uniform on Tuesday night, facing Oakland’s LHP Sean Manaea (0- 0, 7.20). O’Sullivan last started on July 6, 2015, with Philadelphia. For Manaea, it will be his third since being recalled from Triple-A.