There isn't like a sure fire, 100% way to change that, it could be that you are burnt out and could use a break, even if it was only 4 game if it was four lost games it could probably have been building stress unbeknownst to you since the second loss or so. My advice take a break for a bit, it doesn't even have to be a long one like try an hour or something get some water, watch some youtube, listen to music, or even analyze how your game went and try to critique what you could have done better to improve chances of winning.
I am sorry if I couldn't give you the exact answer you were looking for, or the fact I have been rambling on here, I just understand the feeling of losing a series of matches. I just hope what I wrote could be put to some use Summoner.
See you on the rift someday