Open Question: i cleared up all of my acne a while ago, so why is it back? HELP PLEASE!?

I am 14 years old. I had a lot of pimples, but I removed it, when I was 13 years old, but remained clear. About a month ago, in my time, I broke out. I usually clean up within a couple days, my skin returned to normal. But this is not the case. This is only getting worse! I have been in my forehead that these huge cystic zits. I do not know how to do! I did not skin care, diet, stress, or any other change I can think of! So why do I suddenly have acne? ? Please help me! I have always felt myself so bad recently due to the recent acne. : (