NFL Network Insider Ian Rapoport reported that Bryant went to the doctor on Monday morning, according to the player's agent Tom Santanello.
One teammate told Ed Bouchette of the Pittsburgh Post-Gazette that Bryant "called in sick."
"No, he's not here," guard Roman Foster said of Bryant. "I don't know what happened. I think he called in sick today. I don't know. I just wish he were here to answer his own questions. You can't throw that stuff out there on social media land and expect no forest fires behind it."
Bryant's doctor visit comes a day after another disappointing outing. The 25-year-old receiver then went on Instagram on Sunday night and responded to someone who wrote to him "JuJu's better," regarding rookie receiver JuJu Smith-Schuster:
"Juju is no where near better than me fool all they need to do is give me what I want and y'all can have juju and who ever else," Bryant wrote in a post that has since been deleted, via the Post-Gazette.
Later Bryant followed the deleted post with a more positive take:
"[JuJu] is the future and got great talent and is going to be one of the best to play the game I want him to get his I just want mines period point blank ain't nobody did nothing to get me back I worked my ass off to get myself back with no help and little support period in due time the process will show," Bryant wrote.
Smith-Schuster told ESPN's Jeremy Fowler on Monday he didn't take Bryant's comments personally: "There's only one ball," the rookie said.
The controversy and doctor's visit come after a week Bryant spent dismissing the notion he wanted out of Pittsburgh. Rapoport first reported that the receiver was unhappy with his usage.
After a return from a season-long suspension, Bryant hasn't produced production, and he's seen his playing time dwindle the past few weeks. In the last two games, he's earned just three combined catches for 30 yards. He played just 34 snaps in each game.
With the trade deadline at the end of the month, Bryant's name is sure to be bandied about in rumors. A playoff team like Pittsburgh, however, isn't likely to give away a low-cost, talented depth option unless things get uber bad.