Acne Breakouts. For these breakouts?

I have oily skin with comedonal acne. I suffered from acne when I was in my teens and also had a bad period of breakouts in 2011-2012. I started applying Erytop cream all over my face every night to control this. It reduced the pimples but didn't do much for the comedones. On the guidance of a doc, I have been applying glyco 6 cream in morning with sunscreen (SPF 60) and tretinoin A (started with 0.025% and gradually increased to 0.1% and 0.05% alternate nights) in the evening since November. My forehead has improved vastly of the comedonal acne. My left cheek has more comedones than my right. In April end I suffered a bad breakout with big red pimples which have left several marks. I thought it was due to the heat. And this past 1 week I suffered a break out again, mostly on my left cheek, where some pimples coincide with location of the comedones. Am I purging so late in the game? Or is there another reason for these breakouts? Any help is appreciated.