I can't seem to get rid of my yeast infection, i always get treatment but a month after it back, what could be the causative agent?

Yeast infection: Assuming you are referring to vaginal infection, the best way to approach this is to have your sexual partner(s) apply an antifungal cream or ointment to their penis twice a day while you are being treated, and treat yourself through one menstrual period. Although this is not an std you can be recolonized by the yeast present on your partners skin, and also true for bacteria with bv. Good luck.