Overuse injury? Try changing up your exercise. It could be anything. Maybe tendonitis of some sort? Or maybe you need better shoes?

Do strength training too. Calf raises in steps are good. Calf raises on a platform or 45 lbs plates and the Smith machine work too.

Calf injuries can just linger and linger. When baseball or football players get calf injuries they can often be out 4-8 weeks until they come back, and even then it doesn't seem like they're 100% for the rest of the season. Take a lot more rest if it is really problem. Try swimming or something to substitute.

I have been experiencing calf pain when running for 8 months. It's not every time, sometimes the stretches I do beforehand work to avoid the pain. I start my run pretty slow, but I live at the bottom of the hill and I can't avoid having to go uphill for the first 10-15 minutes. Any other tips?