I was woken the other morning by excruciating cramp in one calf. 2 days later and it is still painful so I assume I have damaged the muscle somehow. Do folks just train as normal? Take it easier? Stop entirely?
Rarely, I’ve had delayed onset muscle soreness (DOMS) after a bad cramp, particularly if it lasted longer than usual. It’s similar to DOMS after weight lifting. If you think that is the case, some easy spinning is likely to help.
I did do a gentle ride yesterday… Today has been chopping down a tree… Will do another spin tomorrow.
Maybe I suggest a new feature: “failed workout due to being middle aged” 
It has happened to me a couple of times. I don’t really adjust my training because of it. I do supplement with magnesium to prevent it from happening again. It usually helps.
Even walking is difficult on day 3