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Poor Louis!

Sandra Bullock may have been calm, cool, and collected at the Oscars Sunday evening - but the single mom was overheard telling a friend that the days leading up to the awards were anything but tranquil.

A source tells Us Weekly that the Extremely Loud & Incredibly Close actress, 47, chatted up a pal during a trip to the bar inside the show. When asked about Louis, she admitted her 2-year-old son had fallen ill earlier in the week. "The scariest thing happened the other day," Bullock revealed. "Louis had this really high fever."

Continued the Blind Side star, clad in Marchesa for the big night, "I kept trying to break it with Tylenol, but it wouldn't work! I was freaking out that he might have a seizure...I was about to jump in the car [to take him to the ER] when his fever finally broke. He's fine now, but it was so scary."

Like any proud mom, after sharing the details of her stressful day, Bullock couldn't help but wrap up by gushing about her growing toddler. "He's getting so big!" The star exclaimed to her pal. Pointing to her hip, she said, "He comes up to here on me now!"