Help 36 w

Sweats, feeling very thirsty, nauseous when i eat?? I had all this 2 nights ago but it went away but i also had severe right side back pain so i went to hospital results said i had no uti or kidney infection but now it burns when i pee with all the same symptoms again and mild back pain but ive never gotten those syptoms with just a uti alone(Been to hospital for over a week back and fourth and they keep telling me urine culture is clear)