I suddenly woke up from sleep with very sore calves, making it difficult to walk. Why is this happening?

Honestly, I don't do any exercise or anything like that, I just...

I woke up from sleep, and suddenly my calf muscles whenever I walk

It becomes stiff and painful to walk. My calves feel somehow...

It feels like it's tightening. When I touch it, my calf muscles are firm.

It seems like it's all bundled together. When lying on the bed and relaxing, it gets better again.

When I try to get up and walk again, my muscles suddenly tense up and it starts to hurt.

I've never experienced a situation like this in my life, and I wasn't overexerting myself during exercise either.

Suddenly, I'm extremely confused. Why is this happening?