3rd Flush - Why so tired the day after?

I have just done my third flush in a year, using the Epsom Salts - tumbler of grapefruit juice + 2 tbl spoons of olive oil + a little water routine. This time I found it impossible to consume more than two-thirds of what I had managed previously, and the next morning I had a splitting headache and felt wiped out (and a bit depressed) for the rest of the day. In terms of results: I believe there were the same amount of stones etc. and I feel fine on day two, but I really would like to know if it could be made easier next time. Is there any preparation to the flush that would reduce the mid-flush nausea or the day after tiredness?
If someone could explain this particular reaction I would be really grateful. Tweet