The rashes are something arising in your body as it purges and cleanses itself, like the protein-scum that arises on a pot of simmering lentils or chicken. They stayed with you after because you didn’t go for quite long enough for the body to finish that process, just go a bit longer next time; yes it’s true that a critical point of healing and cleansing is the 7th or 8th day.
It will definitely heal you skin if you go for long enough. Bear in mind that if you’re sensible you can go safely for at least two weeks which means that the body may need all of that time to fully cleanse some issues. I had some backne before I did a 12 day and by the end all that could be seen were some red highlights under the skin of where the worst offenders had been. Sometimes we need to think of d.fasting as a treatment that needs several applications: as we re-feed the old problems can return, but as we keep hitting them with 7 to 14 day to even longer d.fasts, pretty soon they will be defeated.
I was on a 5 day dry fast and when I ended it I went out to a restaurant next day… had truffle fries with parm cheese sprinkled on top, and the following day my skin broke out. In rashes. I thought to myself this was my microbiome being wiped out from fasting & related perhaps. Mind you, I had no dairy in my diet for a long time prior to the fast so that was a mistake the way I broke it. But the rash went away the next day after and then everything went back to normal.
Don’t know where you got the idea that a cleaning cycle is 7 days? But chances are it’s a detox/healing process. Remember the goal isn’t to achieve perfect health in one fast. Your better finding a healthy sustainable routine where you implement it. And get ready for the long road. These things take time, lots of time.