Your liver is now getting clean enough to start working on the metabolic waste that has clogged your other systems for so long.
I think your experience is typical.
Let your liver work on this metabolic waste for a while and then flush again. Using just this as a gauge, I suspect I may be nearing the end of flushing (with the exception of maintenance)... or at least getting clean enough that my liver can finally keep up with its monumental tasks.
I suspect we can use our ability to breathe freely as somewhat of a gauge to our need for flushing, recognizing of course that there are other factors that may cause restricted breathing.