Answer:Researchers say a psychiatric condition characterized by a person's mistaken belief that he or she smells bad is vastly under-recognized. Called olfactory reference syndrome, the condition is "probably very common," says Katharine Phillips, MD, of Rhode Island Hospital in Providence. so you might just be thinking thst in your head man. just shower, brush teeth etc... or this could be a possibility...What causes the unpleasant smell is the bacteria that build up on your sweaty skin and react with sweat and oils to grow and multiply when sweat reacts with bacteria on the skin. These bacteria break down proteins and fatty acids, causing body odor in the process.