Irritable Bowel Syndrome Treatment

I was given:
Keflex
Bactrim
Zithromax
Genamicin
Penacillin
all at different times to get rid of an infection that I still HAVE!
Plus I was told to eat lots of Yogurt to not get a Yeast infection.
so Im wondering:
Am i defeting the purpose of the Antiboitics by consuming the yogurt which load you up with probiotics.
as this is the FIRST time I have ever NOT been able to rid myself of infection and used Yogurt at same time.
anyone know about this or can dirct me to a site for answers.
Please, thanks!