Sorry to hear about your symptoms. Please keep in mind that I cannot accurately comment on your condition as I have not personally reviewed your films nor have I examined you. Myelomalacia is a general term for softening of the spinal cord and can be due to a number of different conditions including disc disease. In your particular case, it seemed to have
stemStem cell research from the disc injury sustained from the car accident. The damage as you describe are only limited to the areas of the involved discs. Therefore it is unlikely that you have a primary neurodegen disease which would be more spread out throughout the spinal cord. In terms of progression, it should not extend beyond the affected areas. However, the existing area of encephalomalacia can begin to shrink if there was extensive disease from the cord impingement. This could result in weakness of your arm muscles, but the myelomalacia itself does not typically cause any kind of pain symptoms. If the nerve roots that exit the spinal cord were involved at all,t hen yes it can cause pain but not the cord itself. It also shouldn't affect the symtpoms of pain in your legs.
HOpe that helps.