Still breaking out, week6 on accutane?

I wigh 65kg and are currently on 40mg of accutane a day My acne is moderate kinda bad, but not the worst. My derm said i should see a 50% improvement by week8 but soo far i have just hadda secong break out about 5dasy ago (week 5). My cheeks got many big red "VERY SORE AND ITCHY" pimples and a few more around my chit (i dont ussually get them on my cheeks). Im wondering why im still experiences breakouts?? Some really big infected areas on my face have had much improvement soo far thoe. And by back has cleared ..?