Ben Pollock was named on Hereford's team sheet but manager Josh Gowling decided not to risk playing him
"It was a difficult one," said Gowling.
"We trained this week and then it was brought to our attention he had a headache yesterday.
"Today he's told us that.
"I'm not going to risk any players.
"First and foremost we love football and it's our passion.
"But he's a human being and you've got to make sure he's right.
"So from my point of view it was a no.
"I can stand here and speak to you guys and the fans and look at his parents in the face, if he's gone and headed the ball and we don't see him again.
"So I made that decision, he wanted to play, but we said no.
"We need him to be right. Hopefully he'll be ready for Tuesday.
"He went to the hospital today to get another check-up and they said he's okay.
"But until he's back playing with no symptoms he will not be available for selection."