Sasha Pieterse tears up over health problems, opens up about losing 15 pounds since joining 'DWTS'

Sasha Pieterse got emotional on Tuesday's Dancing With the Stars when she opened up about her recent health struggles.

Before she and pro partner Gleb Savchenko took to the stage to perform a samba set to Hailee Steinfeld's "Most Girls," thePretty Little Liars star opened up about why she felt a connection with the song in a pre-taped segment.

"I love the song because it really resonates with me about what I've been through, and what I'm still going through," Pieterse shared.

Speaking with Savchenko during rehearsals, the actress fought back tears as she opened up about her weight gain and the painful insults she endured because of it.

WATCH: 'Pretty Little Liars' Star Sasha Pieterse Dishes on Joining 'DWTS'!

"I gained 70-ish pounds over two years," Pieterse recounted. "It was really, really hurtful the way people reacted. They were saying stuff like, 'She's pregnant.' 'You're fat.' They were angry, they were mad that I look like this. It was one of the hardest things I've ever been through."

The 21-year-old actress said she had no idea why she suddenly started putting on weight, and had no idea how to deal with her problem until just recently, when she was diagnosed with Polycystic Ovary Syndrome, a hormone imbalance.

"Finally, I knew what this was happening to me," she shared.

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Since starting the show, Pieterse said she's already lost 15 pounds and "most importantly, I'm feeling like me again."

"It's not an easy road, but being able to focus on getting myself healthy again and the fact that I'm seeing results now and getting better is all I can ask for," she added.

Hitting the dance floor for their prom-themed routine, Pieterse absolutely beamed as she and Savchenko pulled off a beautiful, strong and dynamic samba that earned some love and praise from the judges -- especially Carrie Ann Inaba.

"Most girls are sitting at home thinking, 'I wanna be like you,' that's what's happening right now." Inaba exclaimed. "The best part of being a judge on this show is watching someone like you really blossom into yourself. You are great out there."

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Speaking with co-host Erin Andrews after the performance Pieterse opened up about her DWTS journey and her emotional road to getting healthy.

"I feel like I've always been a happy person and I've been so blessed with an amazing family and friends, but I went through a hard time," she shared. "So, feeling like me again means the world, honestly."

For their sweet, energetic performance, the beaming couple earned a score of 22 out of 30, putting them near the top of the night's scoreboard.

Dancing With the Stars returns next Monday at 8 p.m. ET/PT on ABC.