Whats causing me to to break out ??

I just started using epiduo (a acne cream containing benzoyl peroxide ) 2 weeks ago , my acne has gotten worse , but this wensday I went to my Der and she gave me something new to try , it seems like my face has stopped breaking out ... I need help ! Do you think it was just my skin getting use to the epiduo and now its use to it that was causing it to break out ? Do you think it was the new stuff fixing the problem ?
Whats causing me to to break out ??
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