Do I have a ually transmitted disease?

For a little more than a week now I've wondered if I had a bladder infection or an STD. It feels like I always have to pee and when I actually do pee and I'm done it feels like I still have to pee. I've peed in my pants a couple of times because I couldn't determine if I really had to go or not. My pee looks milky. My side is cramping really bad, it feels like a painful runners stitch. I'm sick to my stomach and if I eat anything I'll vomit. I'm not promiscuous or anything, I've only slept with one person, my boyfriend of almost 4 months. Sometimes I wonder if he's cheating on me. I think it's weird that eventually we stopped using condoms, he even came inside me once. Then last week he bought a big pack of condoms, like we still use them, and when we were making love we ended up taking it off anyway. Soon after is when I started having this pain. Please help me!