"The doctors told Brooke on Sunday that if she wants to get better she has to reduce stress and get a lot of R&R in the coming weeks," a source close to Mueller tells People magazine. "Her mom is checking out spas around the country now."
According to the magazine, Brooke is suffering from pneumonia in both lungs and has been treated in a Los Angeles hospital for nearly a week. The original infection came after Brooke underwent surgery for an impacted wisdom tooth.
Mueller's docs are "not happy" with her slow recovery -- and believe stress on her immune system is preventing Brooke from getting well. The physicians are also concerned about her physical and psychological health.
"The doctors basically said Brooke is not going to get better without taking her health in her own hands and reducing the stress surrounding her life," the source explains. "She has to do it now."