Maybe selenium supplement (or some dietary equivalent from herbal sources) is resulting in body odor (e.g. you know how asparagus gives funny smell to urine). Sulphury foods can also produce strange skin and sweat odors. It could be also some pheromone which may not even have any consciously perceptible smell, while still affecting those around. Drastically changing body chemistry can cause effects of that kind.

My mother was a medical doctor and she mentioned many times she could smell a person with cancer after a brief moment of being in the same room. She said it never failed her. In few cases in which the initial tests have returned negative result, she would persist with tests and followups and it would invariably turn out that her smell hunch was correct. Yet the smell was so subtle, she couldn't describe it or find any analogue.