Don't worry there are lots of other drugs they can give her. Just make sure next time you go to her primary care that they mark on her chart that she can't tolerate Biaxin or you might forget and give it or erythromycin to her again some time. Not dangerous but sure makes you feel stupid when you figure it out ("oh yeah, I remember now, this one vomits with Biaxin - DUH").
I know it feels sometimes like if you drop one of the balls you are juggling, this whole miracle of having your H back may evaporate. I live with it too. It does get better with time, I think - and with the confidence that our changes are for US, not for them.