What does this mean?

I always have this situation whenever I take off my undies and this always bothers me. It has a sweet soury like smell, powdery texture.

What does this mean? Do I have an infection? Or its just normal and I am overthinking things.

I have this since grade school.

I dont usually post or say anything in groups but I want to hear your opions on this. I posted this because I am to shy to ask for consultation with a doctor.

I am still a 20 yr old student.