Went out for routine run last Friday and after 1 mile, calf muscle suddenly tightened. Carried on running (as you do!)and it just got tighter, so stopped. Next day it was fine, a day later I tried again and it went again. 2 days later the same. As with most runners, I want to get back into it, but don't know how long to leave it.
PS I'm as fit as I've ever been - a week earlier did a PB at Chicago