How do I have my auto injury case reopened.?

2 years ago, I was in a very bad car accident which my vehicle was totaled and I sustained injury to my arm and right leg. I was out of work for 2 months, and due to lost wages and no income and excalating doctor' bills I settled my case. I continued to experience pain in right shoulder and shortly afterwards they found out that I had a rotator tear to the arm. I had to have surgery to repair the injury since then I have continued to have pain to my right shoulder. I am not able to lift anything of weight with my arm or often times unable to lift my arm over my head without pain. I am not sure if at all possible if I can have my case reopened for other medical expenses. Please help