Hi, Covid19 infection indeed is linked to a particular odor that can be picked up in breath, urine, feces and underarms. We are training detection dogs to pick up Covid19 infection based on underarm odor sweat. And that goes pretty efficient with a success rate of 84 to 100%! In fact every virus is linked to specific volatiles being secreted. This has been shown for influenza virus, as well as the adenovirus, the respiratory syncitial virus, and the parainfluenza virus. And now also for Covid19 virus. It's mostly only dogs that pick up this scent, but I think us humans should also be able to notice it, such as in your case.  It could also have to do with medication intake that changed the microbiome or metabolic processes in the body. I frequently hear people that notice a change in odor after intake of medication, stay in the hospital or prolonged periods of illness.  Best, Chris