Matchmaking

Hello guys, I just want to ask, did riot made some matchmaking changes in last two weeks or what? I was silver 4, everything was fine, i was climbing up step by step, i reached promos to gold in few weeks and then something happened. I dont think I lost my skills in one day (or one hour should I say), be cause now I have about 10/40 win/loss and probably soon I will reach bronze. I know it's only silver, but my score always positive, I'm the guy who trying to carry every game, sometimes I got about 15/2 or even better score, but my team still lose. Always. Just had another game, I'm not even mad now, be cause I get used to, top - 0/4 bot 0/4 0/2 jngl 0/2 me - 4/1. Why? Last year I deleted league for a 2 months when something like this happened. Should I delete it again? Or it's be cause I did not pay anything to riot? I didn't buy any skins etc. Maybe should I? Irony. But guys, it's just ridiculous.