Post-ankle surgery stiffness

i had an operation to remove floating bone from my ankle earlier this year and it now does not have a full range of movement. for example when i raise my toes or bend forward at the ankle there is a tightness/stiffness that i feel right where the incision was made on the outside of my achilles.

i am wondering if i should be trying to increase the range of movement by stretching it slightly every day or whether this will just make it worse. also any excerises you could suggest?

thanks!