When it comes to your nausea I have few ideas of what causes it. I only know that I have given kids one capsule or two of borax with great benefits, no nausea; they usually react very quickly if you give something they cant stomach.
I have on purpose overdosed borax on myself as I like to know what I am dealing with; 6 capsules a day for 10 days caused a little dry skin and mucous membrane in my nose. Gone in two days when I discontinued.
maybe your system is so messed up that it cant take it:
In the same way as Iodine upset a lot of folks in the beginning. You have a mold story; right?
ps the taste of borax in water is not to my liking thats why I prefer capsules.