What the hell is wrong with my MMR?

So today I played a few league games. Two of them were wins, three were losses, and I went from 50 lp to 12. You'd expect me to be on a huge loss streak for that to be the case, but when I checked my OP.GG page and selected "ranked solo", I counted up my games. Of my last 62 games, if I counted correctly, 39 were wins and 23 were losses, putting me at a ~63% winrate. My overall winrate for the season is just shy of 55%. Why am I getting so royally fucked over here? I'm seriously having trouble wrapping my brain around it. I feel like something here is off. If someone could shed some light on it that would be great.