I Am A Male 22 Years Old. Two Days Ago

I am a male 22 years old. Two days ago I started feeling a sting in my urethra so i went to get a std check and they came back negative. This morning when I woke up it burned when I peed and since then its just been lingering stingy feeling at the tip of my penis on the inside. It sounds like a UTI but I have read that men my age don't usually get UTI's. I have passed a small kidney stone before and was told by the doctor that I have kidney stones. Could this be because my kidney stones? or could the std test be wrong?