Help! reoccurring yeast infections

so i’ve been getting yeast infections a lot recently but i don’t know what i can do to stop this. I have only had sex with my boyfriend and he had no STIs etc and i know it’s not that. i use cotton underwear etc but these yeast infections get worse each time. The itchiness is so bad i have to apply cream to it minimum 5 times a day. The doctor prescribed me treatment for it early this week and i’ve since gotten another treatment. Could i take this luther treatment today as the last time i took it was monday or do i have to wait ? also does anyone know how i can stop this because it’s reaching a point it’s disturbing my daily life.