Why wont my mmr go up?

Even after going on a 7 game win streak my mmr seems to have not moved or even gone down. Now when I look at my profile I'm being told that my rank is being shielded but have lost too many games to remain at my current rank. I have a 71% wr out of my recent games, it's legit impossible to climb on this account now since I only get 15lp per win but lose around 22 from loses.