Is there a doctor in the house?

Okay, I really don't understand this.

Whenever I go for a long run ("long run" in my book = 3 miles), I experience the strangest sensation afterwards. As I'm cooling down, stretching, and then getting ready to get in the shower, the smell of ammonia fills my nostrils. I've asked other people nearby if they smell it, too (most notably my lovely wife - I can count on her to tell me when I stink!), and get rather strange looks in response.

Nope! Nobody else near me can smell it. Is it all in my head?

My friend Chris is a Navy doc and a pulmonologist. I asked him if he had ever heard of anything like this before.

Nope! He's never heard of such a thing. Maybe I'm just crazy.

Does anybody else have this problem? Does anybody else know what causes it?

I can live with it. It's just weird and I don't know how to explain it.