cycling to running calf issue

Hi,
I'm 70 years old, I cycle around 180 to 220 miles each week, around 6 months ago I started to get back into running but am constantly pulling what appears to be the inner calf muscles often on both legs. I have visited two physiotherapists and followed their advice. Within this advice was the purchase of new running shoes and additional orthotic inserts. I appreciate that my high mileage cycling will have an effect on how my calf muscles perform and believe this is the main reason for my problem. Any ideas how to resolve this problem. I'm planning a long distance cycle ride so cutting back on the cycling is not an option at the moment but the calf problem is getting me down. Any help appreciated.
Cheers
Mal