Yeah i know the exact smell that you are talking about & it always comes with W.D's! Its nasty & it always makes me feel worse then i am already feeling!
I think the smell is all the toxins leaving your body, well that is the only thing that i can think it might be! It always seems worse after i've been sleeping.
My Boyfriend & i have both used heroin
for years & we both suffer from that same problem. I'm always paranoid that the smell is really strong & that everyone can notice it off me so i'm always showering & scrubbing myself! My Boyfriend worries about the same thing.
But hand on my heart i can never notice the W.D's smell off him & he sez that he can never notice it off me. So it seems to be something that people notice off them selves.
But it is an horrible feeling when you wake up in the middle of the night, normally from a terrible nightmare, & then when you wake you feel sick as hell with W.D's & then to make things worse you get that W.D's smell, i do sit up in the bed close to tears & think "How the hell did i get myself in this awful mess........"