Amy Schumer reveals her son was hospitalized with RSV

Amy Schumer, who hosted "Saturday Night Live" for the third time this weekend, had to miss a day of rehearsal in order to take her and husband Chris Fischer's 3½-year-old son to an emergency room for a respiratory infection.

"This was the hardest week of my life," the Rockville Centre-raised comedy star, 41, wrote Sunday on Instagram. "I missed Thursday rehearsals when my son was rushed to ER and admitted for RSV," or respiratory syncytial virus, a common childhood disease that while usually mild can lead to bronchiolitis and pneumonia, according to the federal Centers for Disease Control and Prevention.

A photo on Instagram Stories, where posts cycle out after 24 hours, showed Schumer wearing a surgical mask, dozing on a hospital bed, with son Gene lying atop her, an oxygen mask strapped onto his face. "This was our Thursday. Rsv is not [messing] around," Schumer wrote across the photo in graphical text.

"Shout out to all the parents going though this right now," the Emmy Award winner said in her main Instagram post. "I got to be with him the whole day at the hospital and the beautiful humans at @nbcsnl couldn’t have been more supportive. My son is home and better."

Schumer added of "SNL," "The reason this show is so fun to do isn’t actually the performance or the show itself. It’s getting to spend time with the people there. The cast and the writers of course but the people who are behind the scenes making it run smooth are my favorite. The crew! Donna. Jerry. Jodi. Genna. Tom Wally and on and on," she wrote, evidently referring to costumer Donna Richards, key hair stylist Jodi Mancuso, stage manger Gena Rositano and others.

Saying that show creator and executive producer Lorne Michaels "has assembled the most talented people with the kindest hearts," she went on to thank "everyone there and to the doctors and nurses who helped us." She did not specify the hospital.

"Proudest of you on Thursday than I have ever been," commented her friend, cookbook author Jessica Seinfeld, wife of Massapequa-raised comedian Jerry Seinfeld. "Treating every nurse and doctor with warmth and appreciation whilst you were melting from fear and stress. You made the obvious choice to stay with Gene over going to SNL rehearsal that day, and you still managed to absolutely kill it last night. Blown away by you, per usual."