Can someone explain to me why the body of the honored lady is always in pain? Is that beca...

I Believe so

yes, it's because of the poison

But he was poisoned ages ago... How can the poison still affect him? :O

that thing he was just him remembering past, war and etc. when he was announced as honored lady he should have paid visit to concubines so they poisoned him with tea or something. it was later that day when symptoms started revealing

If I remember it correctly, someone said that he hasn't completely recovered from the poison yet, 'cause it's a really strong one. Since the emperor is the one inside his body, he could withstand it as if it was nothing. It doesn't help that the only time he took a medication was that time Sunyoung force fed him. He should have kept on drinking his medication to heal faster, but he didn't since he's strong enough to fight the pain. But now that they have switched back, Sunyoung who's significantly weaker than him is suffering a lot. Basically, the pain prolly never subsided, but they have different tolerance for it.

Oh my, your explanations is really good even if I understand everything after reading manga I really like your statement
(=・ω・=)

OMG thank you! I finally understand! Thank you so much for wasting your time to explain this to me ⁄(⁄ ⁄·⁄ω⁄·⁄ ⁄)⁄