its just, with repeated courses of antibots her own iimmune systemn will be low... so anything you can do to boost that is good right now. im sure you are already, but take a look at diet, supplements maybe, and if you can get a recommendation for a good homeopath or whatevr, that would be good i think.
when i was a kid (well, still now i guess) i manifested stress as illness. i got tonsillitis, pleurisy, flu's shingles... all sorts when i was particularly under pressure... any chance she could be upset about anything? divorce or something? maybe try talking to her about anything that may be upsetting her. i know all that sounds a bit far fetched, but i only say it from personal experience
hope she feels better soon anyway!