Huge win streak with 14 game loss streak after?

So I've been learning a lot about this game, I even hired a coach to help me too. Because of my coach After a few weeks/month of coaching I thought I was finally improving with this game. After that my coach said "Keep doing what I've been teaching you and you should be able to climb very fast." So I played more and won some more. I came back to league a week later because I have school during the week and I played 7 games and lost all of them. I'm not the kind of guy to tilt so I remained positive, I decided to play more. The next day I lost 7 more.... I don't like to blame my team but these past two days in 80% of the games my team was probably the worst... Because i lost so much I looked on the forums and people have been going on win streaks and then horrible loss streaks, it's not only me.

Is there something wrong with the League of Legends matching system? It's like they don't want someone to have over 60% winrate. I really feel its just the system Riot games implemented into LoL. Any thoughts guys?