Hi i'm 21 years old and i rarely ever drink. but when i do i get a severe soreness in my lower left side of my back.can you tell me why or what it is?

Need more info : I'm not sure why you have that low back pain, but it's certainly not your kidneys, if that's your worry. More likely it's from muscle strain; but I don't know what your infrequent drinking has to do with it unless you can give more information. See your clinician for a more detailed evaluation & explanation. Hope that helps.