What might this be.... a pain in my left side?

I have a pain in my left side... kinda lower and to the front. I'm an athlete so I supplement vitamin B12, creatine, and recently some caffeine and gugglesterones. I'm thinkin this my be the cause of it, but do I have anything to worry about?? e.g kidney, liver failure etc. It doesn't hurt much (I can take some pain)... but its annoying and it IS noticable. Should I go to the ER? ... I really don't wana ignore somthing that might kil em??? Sorry if I'm blabbering, I'm a little drunk. All answers are appreciated.