'Dancing With the Stars' contestant Sasha Pieterse talks health scare and weight loss

— -- "Dancing With the Stars" contestant Sasha Pieterse has been struggling with a health problem for the past two years, she revealed last night on the ABC show.

The former "Pretty Little Liars" actress said that she suffers from polycystic ovary syndrome, or PCOS -- a hormonal disorder that caused her to gain 70 pounds.

In an interview with ABC News after the show, Pieterse said that actually receiving the diagnosis was "amazing," because she had no idea why her body was changing the way it was.

"It was a difficult process for me because I didn't know how to fix it. There was nothing that I could [do to] help myself," she explained. "I just really want to bring awareness for that too because there are so many women that have that who have no idea."

Pieterse, 21, and her partner Gleb Savchenko danced a samba set to Hailee Steinfeld's "Most Girls" and earned a score of 22/30. The song, which has lyrics including "You know some days you feel so good in your own skin / But it's OK if you wanna change the body that you came in," resonated with her personally, she added.

Now, she said, her body is changing yet again, as she has dropped 15 pounds in just two-and-a-half weeks because of her grueling "DWTS" schedule.

"It's been amazing!" she said.