lp gain-loss

yo guys what's up! i got promoted to d4 a couple days ago. In plat2 i was gaining about 22-23 lp per win.when i promoted to plat1 i was gaining 18-19 lp per win.when i reached d4 i was gaining 15 lp and i was losing 23-25.after 5 loss in streak i gain 12 and i lose 25. what's wrong? anyone knows how to fix this?