How do you climb this season?

I am having a LOT of difficulty sustaining anything positive. My win rate is below 50%, my MMR is constantly dropping, I can't seem to keep a win streak without it being followed by a losing streak that just negates ANYTHING positive I earned. I was an S7 plat and suddenly am having issues with climbing back. I've even had S7 silvers in my matches.

What the crap is going on???? Is my core set of champs just straight garbage now? Am I forced to play these damn meta champs that I genuinely have ZERO interest in? I can't be the only one having this problem. SOS.