What can be causing my ovary cysts, missed periods and acne?

I'm 18 years old and last year I went on to accutane for 4 months, during that time I had very irregular periods. After stopping accutane my periods returned to normal. Then in May of this year I had very bad cramps and had an ultra sound in which they found a small cyst on my right ovary, I missed a period this month. Then after that it returned to normal but started to get very bad acne around my chin again. I've also missed periods for the last two months. Do you have any idea why/what is happening?

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