So I think I have a UTI... HELP!

I've never had one before. It hurts like hell when I finish peeing and I constantly feel like I have to pee! This started yesterday and it's too late to contact my doctors office tonight and I don't think they are open on weekends... Is there anything I can do to lessen the pain?! 
(Also, how will this affect having sex? My boyfriend is coming over on Sunday and it's the first time we will have the house to ourselves in a long time...)