The headache the Steelers are experiencing now is of their own doing, according to someone who witnessed the causes.

The feud that is now enveloping Pittsburgh — Antonio Brown reportedly fighting with Ben Roethlisberger in practice last week, then skipping the rest of the week’s practices, then missing the finale Sunday as the team created an injury for him — stems back to 2012, according to ESPN’s Ryan Clark. The then-Steeler witnessed Brown in practice every day, saw the kind of teammate he was, and now is trying to confirm every “diva” stereotype about the all-world receiver.

“Mike Wallace turned down his deal, and I knew already they were going to offer Antonio,” Clark said on “SportsCenter” on Monday night, referring to Wallace’s 2012 holdout, in which Pittsburgh turned around and gave the $42.5 million it had earmarked for Wallace to Brown instead. “When [Brown] walks past, I say to the strength coaches, ‘When you give him money, you’re going to create a monster.'”

That monster had his sixth straight Pro Bowl season this year, catching 15 touchdowns and racking up 1,297 yards and is, at worst, among the best receivers in football. Yet he also erupted at the close of a rare playoff-less season, missing Saturday’s walk-through and a meeting, then leaving at halftime of the game against the Bengals, according to the Pittsburgh Post-Gazette.

This is the monster they created, Clark said.

“With success, with money, these things come,” said Clark, who was a Steelers safety from 2006 to 2012. “… When it comes to being a good teammate, when it comes to just being supportive, understanding you’re trying to achieve one goal, that doesn’t matter to him. What matters to him is 19 attempts, 14 carries, 185 yards, two touchdowns against the Saints. That’s what’s important to Antonio Brown.

“… Mike Tomlin has to put his foot down and shop Antonio Brown. … This is about the fabric of the team. This is about the guy who goes Facebook Live when your coach is talking.”

There’s only one thing to do, Clark said, with a star the Steelers inked to a $73 million extension in 2017.

“Time for him to go,” he said.