Lot's of people use creatine men.. it's not abt the product, but how you use it. everything have a side effect at a certain point. even water have side effects if you drink to much or something.. but if you used it the right way i don't think there's anything you need to worry abt and if it's really have been a year it's definitely not the creatine. My point is there's no point in worrying, if your not feeling well get it checked and focus on getting better or being healthy in general. Trust me when i say this worrying abt it only makes it worse.