The 22-year-old singer was forced to cancel a tour last year when she found out she had a haemorrhaged vocal cord.
Concerned, she looked to Brit Smith for help - as he had been through the same health hell the year before.
"I was sitting in bed and we were all talking... and I texted Sam and I was like, 'Should I get this done and fix this now...?'" she recalled during a chat with Most Requested Live over the weekend (26-27Mar16).
"He was like, 'I promise you you will sing better than ever and you will be much happier if you get this surgery'."
The All About That Bass star also revealed she's struggling to find a support act for her upcoming summer tour.
"The artists I love, I think, are too big to tour with me," she added. "I love Alessia Cara and Troye Sivan, and both of them are, like, way too big. They can't open for me. They're amazing!
"I just tweeted Troye and was I like, 'I'm obsessed with you, here's my number; please hit me up...!'
"I can't stop watching Troye's videos; they're so creative that it makes me jealous and sad that I didn't put more thought and time in my old videos."