How do you tell if a 3 year old has thrush?

Dd is telling me it hurts to wee. Not everytime, but when it does it really hurts & she asks for a shower. I think the warm water helps I guess.

She is a bit red, but haven't noticed anything else. She says she's itchy, but she doesn't seem to be at all.
I asked if she's been touching it, but she says no & we have 2 other kids sleeping over, so she's been distracted with them.
I'm not sure what to think. Gp/ed is not an option til wednesday & we don't have much to treat thrush here in town. Will give her a few apple cider vinegar baths & see if I can come up with an antifungal cream, but I'm not even sure thats what it is.

Any ideas?