Alberto,
Good to hear you are working with a coach on your running technique.
When you are running is your heel kissing the ground?
If not your calf is contracted all the time.
Would an epson salt bath help?

Good to hear a warm up is helping the situation.
Are you doing any drills?
If you need help on it let me know.
We can put together some things to pair drills and a running program.
Have you gone through the feet and ankle 14 day challenge?
Roop and Jami have a 5 part foot & ankle series

Roop & Jami’s Excellent Foot & Ankle Adventure | Part I