Yeast infection

Im 30 weeks pregnant and i keep getting yeast infections back to back literally! I got my first one and my dr prescribed me a cream to insert, next thing you know i have a uti, so my dr prescribed me some antibiotics which caused me to get another yeast infection so i use another cream insert and cure it, have sex with my s.o and he does cum inside me...two days later i have another yeast infection wtf!? Him cumming inside me never caused me a yeast infection before so what’s the deal and how can i stop them from coming back!