How many loses in a row considered normal in ranked game?

I got a 5 game losing streak today from GM3, loss 18-20 points for each game. I have heard people saying that you might actually loss less points if you did decent despite losing the game.
5 game losing streak is kinda annoying. I am thinking about maybe I was just having bad luck today. Perhaps that wasn't all my fault since I only loss 18-20 points for each?