Vazquez allowed six runs in the first inning of the Marlins' 8-4 loss to the Nationals on Sunday.
Washington's win broke an eight-game losing streak to Florida at home.
In Vazquez's previous start against the Phillies on Monday, he didn't make it out of the fifth inning in a loss to Philadelphia.
"I wish I knew what was going on," Vazquez said. "It's just unbelievable what's going on right now."
Vazquez is one of the most durable pitchers in the major leagues. In 14 seasons, he has 154 wins, but he's struggled with a 2-4 record and a 7.55 ERA. Vazquez also left the team for three days after the death of his wife's relative in Puerto Rico.
"I'm battling out there. I'm doing my best. I'm trying to make good pitches. But it's not working," Vazquez said.
He allowed six runs and six hits in the first inning, and stayed in the game only when Jason Marquis was thrown out at third, trying to stretch a double.
"Believe me. I'm doing my best, but nothing's working. Nothing's working. Nothing. Absolutely nothing," Vazquez said.
Manager Edwin Rodriguez allowed Vazquez to stay on, and he made it through four innings, and didn't allow any more runs, but the deficit was simply too great for the Marlins.
"All we need from him is five, six innings to keep us in the game," Rodriguez said. "But to get behind the game like that's putting way too much pressure on the offense."
When Vazquez joined the Marlins this season, Rodriguez hoped he'd give him innings and wins. That hasn't happened.
"It was a very rough first inning for Javy and that changed the whole strategy and it put us in a hole right away," Rodriguez said.
"He needs to get out of the first inning."
Trying to display some patience with his veteran right-hander, Rodriguez will counsel him.
"We will talk to him. He cares. He's working, but whatever he's doing is not working," Rodriguez said.
Marquis had two RBIs and pitched into the seventh inning. Ivan Rodriguez also had three RBIs for the Nationals.
Marquis (5-1) drove in two runs in the first with an RBI double, and added a single in the fourth. He allowed two runs in the second — one of them unearned — and two in the seventh.
Todd Coffey relieved Marquis and Emilio Bonifacio greeted him by ricocheting a ball off his right elbow, and he had to leave. With runners on first and second, Tyler Clippard retired Hanley Ramirez to end the seventh and pitched a scoreless eighth. Cole Kimball worked the ninth.
Roger Bernadina led off the first with a bunt single, and Jayson Werth reached on an infield hit. Laynce Nix singled to score Bernadina. and after Adam LaRoche walked to load the bases, Rodriguez singled to score Werth and Nix.
LaRoche scored on Jerry Hairston's fielder's choice. After Alex Cora singled, Marquis doubled to left to score Hairston and Cora — but Marquis was thrown out at third.
The Marlins scored two unearned runs against Marquis in the second.
Gaby Sanchez reached on an error by Hairston, and Logan Morrison doubled to extend his hitting streak to 13 games. Sanchez scored on a sacrifice fly by Mike Stanton and Morrison came home on Brett Hayes' single.
The Nationals scored their seventh run on an RBI double by Rodriguez in the fifth, and Florida scored its runs in the seventh on RBI singles by Greg Dobbs and Craig Coghlan.
Washington's final run scored on an RBI single by Bernadina in the eighth.
NOTES: Florida 2B Omar Infante didn't start for the first time this season. He pinch-hit in the ninth inning. Infante and Sanchez are the only Marlins to play in every game. ... C John Buck didn't start for just the fifth time this season. Hayes caught instead. ... Rodriguez said that RHP Leo Nunez, who saved the first two games of the series, wasn't available for Sunday's game.