sprained ankle 4 months

I'm in no way saying that this is what is happening to you, but I had a similar experience.  I sprained my ankle several years ago, and after 7 weeks, was in more pain than when I got the injury.  We tried physical therapy with the resistance bands and insoles, and the whole shebang, yet I still kept getting worse.  They had to do a very painful x-ray, they called it a stress x-ray, where they turn your ankle in ways that are very painful, but allows them to see your ligaments in an x-ray.  It turned out that I had torn 3 ligaments quite badly, and had to have surgery to have them rebuilt.  The surgery was an outpatient surgery, so it was fairly simple.  In 4-6 weeks my ankle was back to normal.  I can not turn my ankle in as far as I can the other ankle, but that just shows me that those ligaments are really tighter.  I no longer have lingering pain from it either.  It's just a possibility, but maybe ask your doctor about doing a stress x-ray to see if any ligaments are damaged.  Let me know how that goes!