Trying to improve ankle mobility

My ankle mobility is so poor that I can't even do a proper squat ass-to-grass since my ankles have trouble tracking my toes. I have tried to improve mobility by doing ankle stretches and exercises but they seem to have very little effect. In addition, any benefit is lost if I am not very consistent with the stretches and I'm back to square one.

Also, whenever I do the ankle mobility wall test or stretch my ankles for any extended period, the inside of my ankle right underneath the medial malleolus has a sharp pain that is pretty temporary. I think it might be a tendon that is too tight? It is more noticeable with my right ankle.

Any suggestions for what I could do to improve my mobility and what might be causing this pain? I really want to squat properly.

Thanks.