I don't think you're alone in this... The stage fright of a musician or stage actor is probably similar. I've had to deal with two blatant cases of writer's block in my life - without running out of ideas at the time: it just didn't work. And very famous artists have burnt or shredded huge amounts of art or never finished it because they felt it was inferior.

You write that you like the conscious process of creation. That distinguishes you from the spontaneous geniuses who haphazardly grab a brush and paint and plaster a masterpiece on the canvas. By chance. That means your art is work. It is soul. Is thought. Yes, well... Soul and spirit are allowed to take a break. They are already reporting for duty again ;-))