OP, I currently have a pretty similar situation to you. I strained my calf about 6 weeks ago and it wasn’t healing like I expected. I went to my orthopedist and he took some xrays and found calcified bone sitting in my calf where it shouldn’t be.
I got an MRI and it came back as myositis ossificans. This is basically a condition where your muscle goes through trauma and the body produces bone where it shouldn’t while trying to recover. There don’t seem to be many great options regarding treatment.
Did you happen to pull your calf recently? I’d suggest at least getting some X-rays.