I'm not sure of any antibiotics that can kill yeast (fungus), but I have taken natural antifungals that have helped a lot. If your doctor won't prescribe a precription for diflucan (antifungal), maybe you can look into the naturals (caprylic acid, olive leaf extract, oregano oil...). My IBS symptoms are very much yeast (fungus) related. I think that's why the probiotics are so successful for many...they are putting good bacteria back into your gut, squeezing out the yeast, where yeast had been allowed to proliferate from things like antibiotics. You may also want to reduce (eliminate?) refined sugar and grains for a little while, as they feed the yeast in your body.