Sea salt is a good source of electrolytes. You can add something like 1/8 teaspoon of Sea Salt to 1 liter of water. Emergen C is a commercial product that is also a good source of electrolytes. Mix up 1 package a day.
Kidney damage is a little difficult to determine. We have had a couple of people that experienced a pain similar to what you would experience with kidney stones after taking a high dose of chlorite. This pain only lasted for a day or two and then it went away and everything returned to normal.
When it comes to young children I tend to be conservative. The half life of chlorite in rats is a little over 40 hours. Drinking lots of water reduces that down to a little over 30 hours. We think the rat data also applies to humans but this has not been studied. In 3 days you will have experienced 2 half life reductions plus a little extra. Since you didn't take a totally toxic amount to start with (you are still alive...) this amount of time should get the levels of chemicals down to a reasonable safe level.