it seems like Jin used to be bottom before, than he switch? hmmm

Yess seems so! i'm suspecting the guy he was on the phone with,the one golfing with the expensive rolex! i have a feeling they might've shared a past,an intimate one probably before he got betrayed by him! ...but thats just my speculation .. i could be wrong

Yeah, that seems like the case. Im pretty sure he is a top but he could no longer feel pleasure from the front so he switched to the back