Hi Amanda! Welcome to the GERD board!
I'm sorry to hear you're having such discomfort.
I haven't heard of GERD causing yeast infections, but I do know that certain antibiotics have been known to cause them. What antibiotic were you on? Have you taken it before?
I'd talk to your Dr. and see if he can try a different prescription. Are your main troubles the IBS & GERD?
I hope you feel better soon! Please keep us updated! :)
Toni