(Concern) Occasionally experiencing pain behind the knee and cramping during sleep

I walk 10,000 steps five days a week.

I do lower body strength training two days a week. Recently, the only change is that I am participating in a running crew twice a week.

The problem is that lately I've been experiencing pain behind my left knee, and a few days ago, I had a cramp in my calf and thought I was going to die.

Last night, I had a cramp in my calf while sleeping, and I couldn't move for about a minute, I thought I was going to die.

What do you all do in situations like this? When you get a cramp in your leg again, what methods should you use and which hospital should you go to?

I'm really worried because I couldn't move at all, and a minute felt so long.

If you have experienced this before, please let me know how you treated it.