MMR Problems

Okay ,so i've been playing for a long time (Season 2) and always been a normal player, i got to gold season 4 and 5, but this season i got plat, but there is something i noticed, the mmr is fucked up, sorry for my bad language , but it is, explanation , i played 3 game 1-2 month ago , when i noticed it, i lost 2 of them (i was 2-5 with for a 35 minute game, and 5-2 with for a game about the same lenght) and after those 2 wonderful lost, i won , 1 game, and my mmr was still pretty fine (even if it was still shit) i went 11-5, with , and then BOOM, my mmr dropped by 100, for no real reason, the game lasted for about 35-38 minute and i was 11-5-11. I just dont understand how my mmr (MatchMaking Ranking) can drop sooo much from a win, and, right now im not asking for a miracle or to get mmr back, i dont care, i just want to understand why, why does my mmr keep breaking for no real reason.

Thank you for your time -