First my body tenses, then, as if of its own accord, it curls up into a ball on the old carpet I'm lying on and lapses into spasmodic convulsions. The pain is unbearable and I'm not occluded, yet I don't allow myself to make a sound. No scream, no groan, no gasp. I endure it stoically until my vision blurs and I feel like I can't breathe.