Not jumping on a bandwagon here Sarge but you have just described what happens to me if I lay on my right side too long in bed.

When it occurs I let out a blood curdling scream as the calf muscle tightens to such an extent I can feel what seems to be the muscle fibres snapping which then entails a week of pain thereafter.

I have discovered if I quickly shift to my left side when it comes on I can curtail it if I'm awake/dozing at the time however if asleep when it happens then its goodnight Vienna.

It never occurred to me that it was sciatica linked, I assumed it was just happenstance of my spinal ops.

Sending you my deepest empathies brother and hope it's not bloody permanent.