LP system

I can no longer gain more than 18-20lp. This all started when i was getting into G4, i kept going in and out of my promos to the point where i was given 2 free wins when i entered my promos. After the rankup i have not been able to get more that 18-20lp and before all the entering and existing of my promos i would usually get 25-27 lp per win. Right now im G2 and i still lose 20lp per loss and its is giving me aids. I went on a 8 or 7 game win spree and my lp remained the same. What do i do plz someone help.