Left side of bladder and left kidney hurts?

I've had this for a few days and im not sure what to do. Im 15 years old and the pain can be mild at times and sometimes i can really hurt. Idk It all started to happen right when my friend hit both my kidneys att he same time. It didnt hurt at first but as the days went on it did. Should I go to a doctors soon? I've started to drink cranberry juice to pee more frequently to see if that helps