A grade II or moderate sprain causes partial tearing of a ligament. The patient has bruising, pain, and swelling. A person with a moderate sprain usually has some trouble
putting weight on the foot, and there's some loss of function.

Patients who have a grade III or severe sprain completely tear or rupture a ligament. Pain, swelling, and bruising are usually severe. The patient can't put any weight on the joint. An X-ray is usually taken to rule out a broken bone. MRIs tell if the ligament is torn partially or completely.

The long-term outcome of your ankle sprain depends on how severe it was and how it was treated. A broken ankle is more likely to lead to arthritis, especially if it's not stabilized with treatment. It sounds like your symptoms are getting better over time. That's a good sign that you will recover without further problems.

Todd O. McKinley, MD, et al. Incongruity Versus Instability in the Etiology of
Posttraumatic Arthritis. In Clinical Orthopaedics & Related Research. June 2004.Vol. 423. Pp. 44-51.