It could be a lower ankle sprain?  Did icing the top of your foot help? https://en.wikipedia.org/wiki/Extensor_digitorum_longus_muscle?wprov=sfla1 https://en.wikipedia.org/wiki/Extensor_digitorum_brevis_muscle?wprov=sfla1 These are some visual aids to the muscles in case it is a sprain - you can then up on YouTube or massagenerd.com for ideas on how to stretch or do self massage to help them get better :).  (I'm a massage therapist)