My girlfriend discovered she has a yeast infection today. we had unprotected sex yesterday. should i be worried and can i get one through sex?

Probably not: Yeast infecitons generally are not sexually transmitted. Sometimes the male partners of infected women develop irritation or itching of the genital area, in which case you can share your partner's yeast cream. Otherwise don't worry about it. However, be aware that STDs can cause similar symptoms as yeast -- so get checked if her problem doesn't clear up quickly with yeast treatment.