Unlike strains, more serious injuries require a more thorough and prolonged treatment. The most severe injuries located around joints usually revolve around ligament injuries, such as an ACL (anterior cruciate ligament) or ulnar collateral ligament tear. These injuries can greatly limit your movement and hurt a lot, and can sometimes leave you with recurring pain for the rest of your life. However, a comeback is possible.
When injured, you may feel sudden and severe pain, swelling within the first 24h after the injury, a loud snap or pop when the injury occurs, inability to put any weight on the joint at all or without pain, and a feeling of looseness in the joint. Serious physical injuries require medical attention and possibly surgery. A physical exam is needed for injury assessment and proper diagnosis, and it may include an MRI to check for potential ligament injuries and an X-ray to make sure a bone is not broken.
The estimated recovery time of serious injuries, such as torn ulnar collateral ligaments require, may be 12-18 months. This ligament helps stabilize and support the arm when throwing a ball or performing any similar motion (the tearing occurs most often in baseball pitchers). The UCL becomes stretched over time due to repetitive trauma or stress, and can end up teared. The treatment of more severe injuries can be nonoperative (pain relief, stability restoring, and strengthening the muscles around the injured spots through physical therapy to compensate for the tearing) and surgical (repairing the existing ligament and reconstructing the ligament by using a tendon from another part of the body or with a donor tendon).
Even in the case of light or mild pain, be sure to take a physical exam and see what can be the cause of the pain. If not treated immediately and properly, small acute problems can grow and pose a larger threat to your health, due to your thoughtlessness and unaccountability.