The Ready State Virtual Mobility Coach is like having a virtual Kelly Starrett in your pocket.
Have you started addressing your ankle?
There are some Pro videos that address different aspects of ankle mobility
Free Your Heel, Free Your Mind
Ankle Positional Fault Fix: Jill Miller Style
Squat Quick Test: Is it your Ankles or Hips?
Case Study: Tight Ankles = Bad Squatting
It should not be painful. There is a difference between pain and a stretch or mobilization.