Thick cheese white present from 5 months no itching. Not sexually active. What could be d cause? Can it affect fertility? 20 year old female.

Yeast. Her symptoms resemble yeast infection, also called candida and monilia. Is she near her period? Has she been taking antibiotics? Does she have diabetes or high blood glucose ("sugar")? These factors can increase the chance for candida. This infection can improve with over-the-counter vagina creams or tablets. If no improvement, then see the medical provider. Hope that helps.
Yeast infection. Hi, it seems you might have a yeast infection, please see your family doctor for evaluation and treatment.
It shouldnt. I would suggest you have a complete exam if you have an abnormal cheesy discharge for so long.