I've had calcified tendonitis twice, both prior to any peptides. And yes, it HURTS!!! The painful part is actually months to several years after the calcium deposits first began being laid down. Their presence isn't actually painful. It's when the body starts to reabsorb the deposits that the pain hits. (And the body needs to do that eventually in order to heal.) Unless you've been taking peptides for years, the deposits were likely there before you ever did your first stick and the pain of reaborption was just waiting to happen.