Yeast infection or Pregnancy?

Patient: Im 18 and I’m supposed to have started my period, but instead there is brown on my pad. But when i wipe after going to the bathroom, theres a little blood on the toilet paper. I’m a strict virgin and have not had a boyfriend ever, but i have masturbated last week. I’ve read that it masturbation can lead to pregnancy, but it’s stupid since i havent had sex and you need sex to make a baby. I also read it could be a yeast infection because there is a bad odor down below as well, please tell me this isn’t pregnancy signs! I’m only 18!