Call for UTI?

So my symptoms started late last night, I'm sure that's what it is. Us women- if you've ever had one before- can't forget the annoying symptoms and "just know" when you get a UTI. I'm wondering because it's Sunday do I wait until Monday and call or would it be appropriate to call and leave a message for the oncall dr? :-/ I'm miserable and have been up every hr during the night. It came on so quickly and I want it gone just as fast...