When I get a yeast infection I have it always starts with an itch on the outside, around the labia. Then, if not treated, it goes inside, vaginally. A whitish discharge can be part of it, as can an ache-like pain. Sex is painful, feels like sandpaper. Some people say the discharge smells "fishy" although I have never noticed it.
Unfortunately I am an expert at spotting them through having so many, so haven't had one get too bad in years, but when they are bad the itch and pain are constant. Sometimes there is a slight burning when peeing, but different from a UTI; more like when the urine hits different areas, it burns.
Hope this helps,
Gin