"It spun me out for a while. You feel so incredibly isolated and alone. Unless someone can see that you have a broken arm or a broken leg, it's really difficult for people to relate to the pain that you're experiencing when it's a silent, quiet and invisible pain."
And although she doesn't often address her health condition, Shailene insisted she always wants to be honest and "open" with herself and her fans because she thinks it's "easier" than putting on a front.
She added: "It's just easier, in my opinion, to be open. I really don't feel there's any need to put on a face or be anything other than who you are because otherwise it's exhausting. You always f***ing remember the truth.
"It's really hard to keep up with the lies or the fabrications or the masks that we put on out of self-preservation. The only person that ends up coming back to haunt is ourselves."
The 29-year-old actress also spoke about her engagement to Aaron Rodgers, as she said she and the NFL star initially kept their romance out of the spotlight, but chose to confirm their engagement because they didn't want someone else to do it for them.
Speaking to The Hollywood Reporter, she said: "When we announced that we were engaged, we wanted to do that only because we didn't want someone else to do it before we did.
"And we didn't do it for months and months after we had become engaged, but the reaction to it was really a lot, and so we were like, 'Let's just politely decline [to talk about the relationship] for a little while and live in our little bubble.' "