Internal memory almost full, no idea why topic

Hi, I have a s3 international version, rooted and cm11 on it. My internal memory is almost full and I can't seem to move apps to external sd card. Also, a few months ago I had 5 gigs of space left, now 900mb... Did a complete whipe and started all over again, but still 900mb free memory. Is there a way I can delete everything, maybe go back to stock an start all over?

Thanks