I had very very severe ankle pain for a year and a half after spraining my ankle. My ankle would be very very painful and then I would have searing/shooting pain up the outside of my calf almost in that groove created on the outside of your leg. Turns out that I had a bone bruise within the joint which was triggered every time I would flex my ankle and out weight on it. I rode in converse with a special high ankle brace initially then transitioned to wrapping my ankle with vetwrap. It gave me enough support to help my ankle but was still thin and flexible. Also riding in tall boots was much better than paddocks and half chaps.
I still get pain occasionally when I’m trying to put my heel too deep or am bracing. Improving my core really helped me to balance better.
Also, I second going to a pt or somebody to help pinpoint what is happening anatomically. I’ve had really bad foot problems snowboarding and part of that was the way my muscles were being used and how tight they were. Working on loosening and training certain muscles can help change the tensions being applied to your joints.