I believe that the boron you are taking will help with the yeast; and possibly also with other fermentation in your body; cancer cells typically ferment; they cannot live long in an oxygen rich environment.
Borax is perfect to combat both; as it has some H202 (oxygen) quality which is bad for the cancer cells, and the yeast cant survive high boron.
I now can have some sugar, wine and even beer without having effect on any yeast in my body.
But for a while it is wise to stay out of sugar.
I also believe that your body will keep this in check when the thyroid is working again; normal temperature is essential for the body to work optimally; the immune system typically bring on a fever to kill bugs and cancer cells.
Low temperature / hypo T. is the environment all bugs (and cancer cells)like.