The symptoms wreaked havoc on Kevin Plawecki, attacking his body before toying with his mind. Fatigue made enemies out of focus and concentration. Headaches lingered.
At times, the Mets' catcher found himself within the disorienting haze of double vision.
"I was starting to think it was something more serious," Plawecki said.
Ultimately, clogged sinuses proved to be the culprit. And in the month since doctors finally came upon that diagnosis, Plawecki's season has taken a sharp turn for the better.
But before that, from early May to mid-June, he lived with the torment of uncertainty. Doctors struggled to find the root cause of his symptoms, which weren't getting any better.
"It's a peace of mind thing," said Plawecki, who is hitting .275 with three doubles since June 15. The turnaround coincides with a period of need.
As the Mets begin the season's second half Friday night in St. Louis, starting catcher Travis d'Arnaud remains sidelined with an elbow injury. General manager Sandy Alderson told Newsday on Wednesday that d'Arnaud had started "very limited baseball activity," but his return still appears a ways off.
That leaves Plawecki to fill the void, a responsibility he appears much more prepared to handle now that he's past his physical issues.
"I think he's certainly feeling a lot better and we're seeing the results of it," Terry Collins said.
Perhaps just as important to Plawecki has been the mental relief of understanding the genesis of his symptoms.
"We figured out what was going on there," he said. "So, once we got the right course of action in there to treat that, it definitely has helped me be able to concentrate much better and helped me get better results as well."
For too long, Plawecki, 24, barely felt like himself. Pitch recognition eluded him for more than a month as he dealt with symptoms. He whiffed more than at any other point in his professional career.
"My strikeout numbers were through the roof that month or so and it was really frustrating because I've never gone through anything like that," he said. "I hate putting blame on something, but it definitely took something away from me when I was going through that period there."
The numbers signaled that something was wrong. The Mets drafted Plawecki 35th overall out of Purdue in 2012, attracted partly by the fact that he almost never failed to make contact. In three college seasons, he struck out in only 3.9 percent of his plate appearances.
As a pro, Plawecki maintained that aversion to whiffs. At the time of his promotion in April, his minor-league strikeout rate was only 10.5 percent. But from May 11 to June 7 -- when Plawecki's sinus issues were at their worst -- he hit .186 and his strikeout rate soared to 31.4 percent.
"I really wasn't able to really recognize pitches," he said. "I was leaving my zone. I wasn't swinging at good pitches. I was trying to do too much too early and I just wasn't getting good pitches to hit. I was missing them. It was frustrating, frustrating for sure."
Since June 15, Plawecki's strikeout rate (8.6) has fallen back in line with his historical norms. He again has become one of the players that the Mets have leaned upon to help fill out an ailing lineup.
"It's one of those opportunities for me to try and perform and show people that I can play here," Plawecki said. "I think that I can, I think I've done that. It's a learning experience along the way.
"But I think this first month, two-and-a-half months so far has been good. I think we've taken a lot of good steps in the right direction, so it's promising. It gives myself a lot of confidence."