Why is my face breaking out so bad?

ok well im 15 and i am about to be 16 in a month and im in the 10th grade... well my 7th and 8th grade year my face was always stayed broke out and i used everything.. and then when i got in the 9th grade i just used a bar of soap and then my face cleared up.. but like 2 weeks ago my face has extremely started breaking out again .. but i dont know why the only thing im using different is a new mostirueriser ... but i dont think that is why my face is breaking out.. like i have always used merle norman make up ... so can some on please tell me why my face is breaking out and what i can do to get it to stop breaking out.. cause i dont want to have my face all broke out for christmas when i have to go see all my family.....