September 10, 2017 12:36 PM

On Saturday evening, Busy Philipps landed in Mass General Hospital after hitting the town in Boston in honor of BFF Michelle Williams‘s birthday.

The inseparable duo was spotted strolling in the Seaport neighborhood wearing a birthday gift from Philipps: matching “Best Friends” leather jackets.

“Found her. Happy birthday to my better half. I love you, M. You make everything better,” Philipps wrote on Instagram.

But later, the night took a turn when Philipps landed in the hospital with terrible pains in her left side, which she said was determined to be caused by ovarian torsion.

“I had a crazy excruciating pain in my lower right side and after a long time at Mass Gen, it was determined my ovary had flipped over — it’s called torsion,” Busy wrote on Instagram, wearing a “Hysterical Female” sweatshirt.

“Mine flipped back by itself and I’m ok,” she added.

Philipps felt fine earlier in the weekend, and the friends still got plenty of quality time together.

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On Friday, the longtime friends headed to Legal Sea Foods in Park Square on a lunch break, dressed in their costumes from the filming of I Feel Pretty, a comedy starring Amy Schumer that’s directed by Philipps’s husband Marc Silverstein.

Philipps had her bright blonde hair sprayed brown, while Williams wore a sequined black dress and a long blonde wig. Thanks to their costumes, they managed to sneak in incognito.

“Apparently, no one recognized them,” a source at the restaurant told PEOPLE. (Philipps’ brunette look is for a character she plays in the film.)

Filming on I Feel Pretty, in which Schumer plays a woman who hits her head and believes a spell has suddenly made her gorgeous, is finishing up in Boston, and is expected to hit theaters in summer of 2018.

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