LP Gain/Loss

So I linked my NA OP.GG and I guess I just want to talk about the higher elo LP gain/loss that's going on, although I have seen many people complaining about it. In my stats for league, I had had an 80% win rate in ranked for the past 25 games, I won promos and got into diamond, and immediately started receiving less and less lp and the lp loss was significantly higher so just wanted to I guess rant a little bit about winning 3 games in a row and getting 14 lp for each and then losing one resulting in -18 and then losing one shortly after that but didn't check the exact number. This makes the game feel so frustrating and upsetting.