During the training, there is a severe pain in my left shoulder (the back part, the part that is in the upper diagonal of the scapula). There is no pain as much as a fracture or dislocation, but I cannot lift the weight I lift with my right hand with my left hand, let me tell you that. When lifting dumbbells, doing barbell curls, your movement forms are constantly wrong because of the left side. I never get into the weights that will create such an injury. What do you think could be the reason, what should I do?