Hello, about a week ago I went to the gym and I did some calf raises with some weights. I felt stiffness and a slight discomfort the next day of course but it has been over a week now and I'm still feeling it. I only feel it when I do specific movements for example twisting my body or sticking my pelvis out. I only feel this in the left side of my lower back and a little bit towards the middle. I'm only 16 too. Please tell me if there's something wrong. Thank you.