Help Needed

This season I started out in the bottom of B5, what some might refer to as "elo" hell. I have since then raised to S3 and her lies my problem, I can't move. I had previous just been on the verge of winning my promos a month ago when I got to S1, but due to unlucky and unskillful games, I dropped only to rise back to S3.

I play a game, I win it. I play a game I lose. Some games I honestly lost, most others are because I can't carry a feeding lane, or people don't know how to team fight. There is a host of reasons why people lose ranked games but my questions is......why is this happening all of a sudden. Its like I was walking air and WHAM, face hits pavement.

Most people would say "congratulations you have found your current skill level!". This is not true. I was almost to Gold 5 several times, but it only seems to be an issue this last month dancing around S3.

Did something happen to my mmr? Did riot change the match making system?

What is wrong and why can't I get back to where I was a month ago?