How much water do you drink? I recommend you increase it to flush out the yeast poison. Going to the bathroom as much as possible should help you feel better too.
I've also found that enemas helped reduce my die-off symptoms considerably. This also helps to flush out the yeast poison, and, perhaps, it may help flush out the yeast as well if you continue doing it long enough. I'm still in the process, so I'm not sure what the results will be.
You may have been overdoing the yeast killer. You could try a lower dose or a different killer.
This is my usual suggestion to people. I recommend that you consider that there may be something else behind your yeast problem. For me it was heavy metals (mercury from silver fillings). I suggest you do some research into heavy metal toxicity to see if it might be the root cause of your trouble too.