It's been about two month since I stopped at same rank because if I lose i Get -20 LP and if I win I have +18 LP and everyone I know gets (+20 _ +29) and (-15 _ -20) like 0tam and few more friends . I was like them (LP) but suddenly it reversed so I wanted to know why is it like this . Currently I'm stuck in Silver 2 (50 - 99 LP) I just can't get in promo.
Thank you for your answer a tips
Watell 
Loves Jesus2 votesAs you win and lose games your mmr changes. More mmr vs a team results in losing more or winning less and vice versa. You are falling or decaying right now, improve your play and beat better teams via matchmaking to change this.
Watell1 votesWhat is mmr ? :D and I not doing bad on game sometimes I carry , sometimes I get carried ... sometimes 6/4/15 or 15/8/4 and I have rarely bad score like 5/10/12. and farm always good 150+ / 200+
Loves Jesus2 votesMMR is match making rating. It is what dictates the skill level of the players you play with and against. It goes up and down considering who you beat and lose to and is invisible. Your mmr is very bad compared to other people in your division so as you lose games you fall faster.
Watell1 votesWhat do I have to do ? Just win games ?
Loves Jesus1 votesYes, and the best route to do that is to improve as a player.
Watell1 votesThanks for your time.