First try explaining to your mother that you do need to go to an OB dr. If she just doesnt want to listen or wont listen and wont take you there are other methods. I'm assuming you are a teen. You can do what I did at that age. Go to your school nurse and speak them about what is going on and that your mother wont listen. Your nurse can contact the local health department and they can come pick you up from school and get you checked out. Its no cost to you and your parents will never know. This comes from my own experiences that me and my friend used to have to do b/c our parents didnt believe in drs and i was prone to yeast infections.
Can you ask your mom to take you to the ob doctor? You should go, its probably just a yeast infection. But you should be checked just to make sure. You said you werent sure if you have a STD, are you having unprotected sex? Im not sure how old you are, you can pm me if you dont want to share too much personal info on the open forum. I would like to help you especially if you are a young person. Im a 44 year old mother of 4. I have two daughters and two sons. My oldest daughter is a teen ager, so I can maybe help you if you need it. K