Swainal isn't the feeling of having done something bad per se, rather something bad having happened to you. The effects of the Swainal are widespread and may remain for some time, although the onset is only momentary at best.
Like all good tales, Swainal is associated with a particular person, but also like all good tales - the feeling exists in more groups of people than one might expect.
"Um, can you hold my seat? I just remembered Swainal last night and.. I... uh.."