What Causes Itchiness And Burning Sensation During Urination?

Hello, I have not been feeling right for about a year now. At first I thought i had an STI and all came back negative. I was just treated for what my doc thought to be BV but it hasn t cured all of my symptopms. When I pee it is burny but not unbarable. It is also itchy and I have increased the ammount of discharge. My neck and back hurt the most and it feels like I have an on going flu. I am constantly nausus and feel weak and tired. Could this be a kidney infection? All of my urine tests have come back normal, but I was fine until I had sexual contact with my partner who has all the same symptoms.