Puberty, and early 20's. I hit puberty really early, and was the first person to have a 'pimple'-and it was humiliating! I compensated by becoming skilled at makeup and learning (what I thought) was good skin care practices. I had a few cystic pimples, but mostly whiteheads/blackheads. By the end of 8th grade, my skin had completely cleared up & I was actually thankful for the early onslaught of puberty. Instead of being freaked out and embarrassed every time I got a pimple, I was able to treat it accordingly & cover it up so that no one knew.
The problem was that I had learned at a very young age that your appearance is ~the most important thing~ (obviously not true) and became OBSESSED with skin care, makeup techniques, etc. to the point where I first started using anti-aging cream at age 15. It was ridiculous, in hindsight, because from 14-19 my skin was flawless-to the point where people would come up to me at work/school and tell my that I had beautiful skin.
Skip to 19. My birthday is on Christmas Eve, so my parents try to mitigate the sadness of not having an actual birthday by letting me ask for higher price things for Christmas. I asked for a clarisonic-and my mom bought me the one for 'acne-prone skin.' This thing was a miracle worker! My skin looked and felt brand new ... for three weeks. Then the cystic acne started appearing. I've always had hormonal acne (and have been on birth control since age 13/14 to help with this) but never, ever like this. It was terrible; painful, embarrassing, and took HOURS to hide with makeup.
The acne problem reached its apex at age 22, I believe. It would take me TWO HOURS to effectively cover up my acne in a way that didn't draw attention to it and didn't appear like I was even wearing makeup. It was terrible. My favorite hobby (makeup and hair) turned into a necessity; I wouldn't even walk to the store a block away to buy food if I didn't have makeup on it. It was so bad that the first time my roommate saw me without makeup, she said (in the most kind way possible): "Holy. Shit. What happened to your skin? You always look flawless, and I had no idea that you were dealing with this."
That finally prompted me to go to a dermatologist, and after five years of hating my skin and my unmadeup face, I'm finally free! Now I know that my skin is very sensitive, and I brought on the cystic acne by being way, way, way too harsh. More importantly, I finally stopped picking at my face. I've accepted that everyone has blackheads, clogged pores, and occasional pimples-clawing at my skin only exasperates the problem.
TL;DR: It will get better! I went from 'kinda bad' acne, to perfect skin, to (in my doctor's words) "You shouldn't have to be dealing with this at your age." What helped me was: not eating dairy, using very sensitive skin products, copiously moisturizing, and using a combination of chemical exfoliation and a prescription retinoid (differin) a few times a week.
Do patch tests. Stop using harsh products. Talk to a doctor. Moisturize even if you have crazy oily skin. Try to narrow down which products make you break out. You're not 'purging' if the purging lasts for months. It will get better. Try to remember that this is the best your skin will ever look-even if it's covered in acne. It's healthy, fast healing, and unwrinkled. I had such bad scars when my acne first started clearing up that i was convinced it would always look scarred. Thankfully, that's not the case! Good luck.