LP dilemma

So, this is my first time posting in the new forum, so I have no idea where to post this. I'm in need of an explanation, or better understanding of what happened with my LP. I've been on a five game winning streak in ranked, currently Gold 4. The first four games, I accumulated roughly 22-24 LP each, which got me to 89 LP. Now what I'm thinking is, "If I win my next game, I will surely be up for promotions." thinking I'd get roughly the same LP for the win. So I'm confident in playing another, I win the fifth ranked game, and I only get 9 LP, leaving me stuck at 98 LP. Now what I want to understand is, why was I gaining 22-24 LP for the first four games and then 9 LP for that ONE game? If someone can help me with better understanding that, I'd appreciate it very much.