As far as your IBS is concerned, taking the antibiotic every few days could really be aggravating your IBS. Because antibiotics wipe out good bacteria as well as bad bacteria, they often cause diarrhea. Taking probacteria like acidophilus (you can get this in any vitamin aisle) will probably help with that. I understand the fear of the UTIs. I take an antibiotic every time I have sex because I'm so scared of getting them as I used to get them all the time. I have problems with diarrhea though and often take acidophilus right after my antibiotic. That seems to help. Sorry you aren't feeling up to speed.