born with only one kidney. Sometimes I still get pains...

Hi everyone.
I am 21 years old. I was born with only one kidney. Sometimes I still get pains in my back that I know are kidney pains because I remember when I used to get them as a child and my mum would have to take me to the hospital if it got really bad. It feels like if I sit up to high it hurts and if I huntch my back to much it hurts aswell so I have to sit in a certain position to make sure there is no pain. If i go into one of the positions it instantly gives me a sharp pain where my kidneys are and I have to adjust to a position so it won't hurt anymore. It usually happens maybe 2 times a year. But it has already happened 4 times this year. The pain can be so bad that it puts me in tears sometimes. I am wondering does anyone know if I should be worried about my other kidney because I only have one kidney?
Thank you