I Began Smelling An Odor 4 Weeks Ago. The Odor

I began smelling an odor 4 weeks ago. The odor has become stronger and more often with time. In the past several days I smell it all day and night. I have come to realize (with help from wife) that it is my own exhaled air that I am smelling. It is a pungent, almost sulpher like, rotted flesh smell that seems to be wafting up from my lungs, not a mouth odor.