Sounds like a calf strain. Probably at the musculotendinous junction and most likely from the deeper muscle soleus. Try some calf raises on a step with a bent knee (about 10 degrees) as this hits that muscle. Focus on control of the down movement more than the rise onto the toes. Progress to rising up on straight knees, then bend them ad lower bent, repeat. 15-20 reps. Then reverse, up bent knees, then straighten and lower straight. Basically get used to swapping ebtewwn the two.

If you must run try a heal lift or running shows with a higher heal section to reduce the stretch. If there's no progression go see a good sports PT.