Most Helpful Guys
Never understood these things, Anyways... first, no Vaginal Yeast Infections don't always occur because of sexual activity but it's seems like it's the case with you because one of the guys that ejaculated in you did indeed had yeast infection. It will happen again if some of the guys you sleep with also has a yeast infection, the best way to stop getting that is by using something called Condoms, very cheap and useful and won't get any diseases or yeasts
Have you recently had a systemic bacterial or viral infection? Have you been treated with an antibiotic? Have you felt stressed recently? Are you diabetic? All of those are risk factors for a vaginal yeast infection.
Yeast infections can also be spread by sexual contact, especially oral-genital contact. If this is what caused the infection, the risk is specific to this particular guy. Perhaps he needs to be treated for a systemic yeast infection.
Most Helpful Girl
Yeast infections are caused by an imbalance of bacteria. Eat some yoghurt and the good/bad bacteria will balance out and you’ll be fine. If it’s not gone within a few days, see a doctor.