Ok, I understand.. it seems I had milder versions of cramps. The one I remember the most was when I basically had to grab the toes of my foot and pull hard counter to the cramping muscle and basically it ceased after several seconds. It was very painful but I didn't know they can be paralyzing.
I'm a very amateur swimmer and I try to understand why people drown from cramp in one leg? Because me being a novice, I learned how to swim without using the legs too much (mainly because it takes skill to coordinate everything well) and one of the very first things was me floating by turning my head hard backwards while standing vertically in the water and sinking in water up to the nose, basically sticking as little of my face above water as possible and IIRC I was floating fine with very little help from hands and no use of the feet at all. That seemed easy, especially in dense cold water..