"It's really bothering me," Whiteside told reporters before the Heat's 115-86 loss to the Knicks. "We're going to figure it out. We're going to figure it out when we get back to Miami and figure out what's wrong."
Whiteside underwent an MRI on Thursday, the results of which have yet to be made public.
Whiteside, who is averaging 14.9 points, 12.7 rebounds and 1.6 blocks per game, missed five games after initially suffering a bone bruise on Oct. 18.
"It has really been bothering me throughout the season," Whiteside said. "... You know, I sat out, I missed them games, I came back, and it's still bothering me."
Earlier Wednesday, Heat coach Erik Spoelstra said Whiteside had been sore the past few weeks and had been using the day after games to rest.
"So this is just part of the process. We anticipated this," Spoelstra said. "Hasn't gotten any worse necessarily, just the schedule hasn't let up, and he really hasn't been able to do two days of work in a row for a while."
The Heat have upcoming games against Charlotte (Friday) and Golden State (Sunday).
The Associated Press contributed to this report.