Hi there, there is a theory that seems to hold considerable weight, through the observation and experieince of countless fasters, that the body doesn't get into serious cleansing mode until the seventh day of a water fast--and that ten day fasts are recommended for this reason. Which would seem to resonate with your experience, of feeling a little less well at the point you broke.
Also, it is wisest and most preferable to never break a fast on a 'low', however you, as the faster, perceive that.
Inevitably, with wfasting, a low is followed soon by a high, and the high demonstrates some level of improved health. And it keeps getting better--perhaps not superficially, but at a deep level, you may never know about.
Unless there is a VERY good reason to quit, such as a -rare- rapid, drastic change in blood pressure (please, everyone, do a curezone search on this, so you know what it means, and are not frightened by the mere idea), it is always best to keep going. There are umpteen things to read on this subject in the Soil and Health Library online, free. The 'stages of a fast' is good material to be acquainted with. Look up H. Shelton, Chrisb1's favourite Water Fasting author.
The earlier time (early days of the wfast, esp. a first fast) can be a great liberator! if you will--and was a very good thing to do, when the "cold" came on.
"Colds" represent the result of congestion/constipation, (not a cause), and are a healing *response* to it, not an illness--the "illness" is already in the past, at the point of the cold; so letting the body go into release mode, and not burdening it with food is a very good path to take.
It sounds as though you simply interrupted a water fast, so to speak, when it was going deeper, and it took a few days to switch back into eating mode. There are a zillion intricate, elegant workings that have to switch from the one mode to the other, to come 'online' again. That's all. I wouldn't overconcern myself with the why of small appearances. (But maybe take them as reminders to eat in a low-mucous-forming way.)
Next time, maybe try ten days? See how the ups and downs go, and you will build confidence in the process. And eat very clean, before then. Just an idea. And re-feed well before a second fast. Often people get into too much bouncing from fast to fast. Most of us are nutritionally depleted AND toxic with too much denatured food, and other environmental toxins, so we are in dire need of nutrition that the body can truly digest and assimilate, and that isn't merely stuffing it full. Don't be too concerned about the need to get from fruit and salad to red meat, as soon as possible. :-)
As a rule, break the fast when you feel on an upswing--this is as close as many of us will ever get to the experience of "true hunger" during a water fast, which is said to feel really good, alive, strong, AND insistent.
Breaking on an Up will fire up the body, and bring it online, quickly. The result will be a much faster return to all systems being Go. And at this point, you have a body that can make optimal use of nutrients, and do much MORE with Less, which is really the natural way.
PS. you might want to examine "nutritarian" as one possible eating style/approach. Many people eat too much protein, and are in fact, systemically congested, when what they really need is more whole-food minerals in their synergistic matrix, such as are found in good quality fruits and vegetabls, and (soaked and sprouted) nuts and seeds.