thank you for your question.
Having an xray was the right thing to have done. In my experience if the condition is not a fracture
then a ligament tear is another possibility considering the amount of pain you are having. The ankle joint is made up of 3 sets of ligaments that connect the various bones. An ankle twist can lead to stretching and tear of the ligaments. You can take pain medication upon consultation with your doctor. It is strongly advisable to rest the ankle , hence it is a good idea to get a cast. The healing can take 2-4 weeks this should be discussed with an orthopeadician.Repeated movement of the ankle will not allow healing to take place and will lead to serious problems in the future.