I am sensitive down there, almost uncomfortable, it is itchy and it burns

Someone please help. I have been feeling extremely sensative down there lately. It feels almost as if I'm aroused but it also feels uncomfortable. I've also been itchy and it burns a little when I go to the bathroom. I've also been feeling and having this constant urge to go to the bathroom but when I do very little urine comes out. And I sometimes get this almost orgasmic feeling like I'm about to have one when I do go to the bathroom more often. I've tried to masterbate to stop the sensation but it doesn't help or make it worse. Even when me and my partner have sex it sometimes hurts and I feel this pinching feeling as he thrusts, even when we try different postions but it doesn't help. I have noticed a cloudy milky discharge when I go to the bathroom. I don't think this is an STD/STI because both me and my partner have been checked.