My son (now 12 and with PANDAS since a baby) has had many problems with sinus fungus and GI yeast as result of abx. Abx can increase the yeast / fungus reactions. We had to do a couple of courses of diflucan, followed by oral nystatin until he cleared - then we We found it best to do acidophilus regularly before, during, and after abx, and to do a dose of diflucan half way through the abx. treatment. I still request a diflucan script with all abx scripts.