WASHINGTON — Perhaps The Home Run That Almost Broke the Internet came with a heavy price. Bartolo Colon’s lower back hasn’t felt the same since the night of that majestic, reality-altering swing in San Diego earlier this month.

Even in Monday night’s 7-1 win over the Nationals, Colon felt his lower back tighten up. So instead of tempting fate, the Mets righthander resolved to make himself nothing more than an ornament during his three at-bats.

“Yes, I decided that because I just thought it wasn’t worth it to swing,” Colon said on the eve of his 43rd birthday after holding the Nationals to one run in seven innings. “I swing at the balls pretty hard and I thought, not worth making my back worse, so I told their catcher from the beginning, ‘Just throw it right down the middle, I’m not swinging.’ ”

Not that the resurgent Mets offense needed Colon’s help, at least at the plate. David Wright, Yoenis Cespedes and Neil Walker homered to propel the Mets (26-18) to their fourth straight win, which shaved the Nationals’ NL East lead to a half-game.

The Mets hadn’t scored as many as seven runs in a game since an 8-0 triumph over the Braves on May 4 — the Mets’ final game before departing on an 11-game western swing that turned their bats into wet newspapers.

Rain delayed the start of Monday night’s series opener by about an hour, but the Mets quickly showed that they were not bothered by the slop.

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Gio Gonzalez hadn’t lost to the Mets since September 2014. In his five subsequent starts against them, he went 4-0 with an 0.97 ERA. But he was chased after allowing seven runs and 10 hits in five innings.

The awakening came against an unlikely foe in Gonzalez (3-2, 2.87 ERA), who held the Mets to one run in 6 1⁄3 innings five days earlier. The Nationals outscored the Mets 16-2 in their two victories at Citi Field.

“It is nice to see, it really is,” manager Terry Collins said. “Gio’s been pitching great, and we just went up there and I thought we put some very good at-bats on him. I thought David’s home run really kick-started us again like he does.”

With two on in the third, Gonzalez left an 82-mph changeup over the heart of the plate. Wright pounced, ripping it to left for a three-run shot.

“That’s something that was different here against Gio than back at home, that he made some mistakes,” Wright said. “Instead of missing them or fouling them back, we hit them, we hit them hard. I thought our at-bats were much more quality at-bats here as opposed to last week at our place.

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Cespedes and Walker followed with hits and Asdrubal Cabrera’s RBI single gave the Mets a 4-1 lead. Eric Campbell added a sacrifice fly, only the Mets’ fourth of the season, to complete the five-run inning.

In the fifth, Gonzalez surrendered homers to Cespedes and Walker, the Mets’ seventh back-to-back homers of the season.

Cespedes, who has an MLB-leading 15 homers, has hit 32 home runs in 97 regular-season games since the Mets acquired him at the trade deadline last July.

Meanwhile, Colon celebrated his 43rd birthday a few hours early, pulling himself out of a personal tailspin. He had allowed eight runs in 9 2⁄3 innings in his previous two starts. In his most recent outing — against these same Nationals — he issued an uncharacteristic five walks.

Colon (4-3, 3.44 ERA) settled down after escaping early trouble, though the Nationals didn’t seem to believe him when he told catcher Wilson Ramos he wouldn’t be taking any swings.

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“After that first at-bat and they threw me that changeup, I was like: ‘No, I promise you, throw it right down the middle,’ ” Colon said through a translator. “ ‘I am not going to swing.’ ”

Of course, on a night when the offense resurfaced, the Mets didn’t need him to swing anyway.