Match Making

I have played this game for about two months now and I am level 30 i understand the game well enough and did good my first few blind match pvp games. Then i played with a friend who has been playing a year now on a few aram games. he says hes around gold level if he were to play ranked. since playing with him the game is consistantly matching me with silver and even a platinum rank player every so often. i cant do anything anymore since playing with my friend who boosted my rank apparently. i should still be in the bronze tier but im not anymore. i get shit on most of the time now and i don't know what to do other then lose a lot and hopefully get my rank down some. What can i do in this situation?