I’m at 40% on the match making certainty meter.

I’ve gone down like 100 mmr in the last 2 days despite the fact that I’ve lost as many games as I’ve won. What’s happening is when I lose I get ducked like 45 mmr but when I win I only get like 25. WTF!? All these games are close games and I play decently. I don’t understand what the fuck is going on