An MRI didn't show anything structurally wrong with Gasol's knee, but the center is dealing with swelling, Hoiberg said.
"There's a significant amount of swelling in there," Hoiberg told reporters, according to The Chicago Tribune. "It's been determined that he needs this week to recover from that. There are different treatment options we're looking at that we'll know more about here in the next 24 hours."
Gasol will miss Monday's game at Toronto and Wednesday's game against the Wizards.
"It's a tough blow. There's no doubt about it. Pau is a guy, especially with Derrick [Rose] out of the lineup that you can run your offense through. With the trip the way it is right now, we're still looking at some different options as far as the starting lineup is concerned," Hoiberg said, according to the Chicago Sun-Times.
Butler, who has missed the Bulls' past three games with a left knee strain, practiced fully on Sunday and is listed as questionable for Monday. Hoiberg said he has a plan for how many minutes Butler will play but wouldn't go into details with reporters.
Hoiberg wasn't certain about Rose's availability for Monday's game. The Bulls listed Rose as doubtful.