My boyfriend has the most foul-smelling bottom. It's so bad that if he sits in my bed wearing just his boxers, I have to change my sheets once he's gone.

I spoke to him about it this evening and he told me that he had showered before he came over and washed his bottom with a sponge and soap. I know that it's not his personal hygiene - he showers twice a day. In three years I haven't heard him pass gas once, so I doubt it has to do with flatulence. He doesn’t have bad breath, so I’m assuming it’s not a gastrointestinal problem. I have entered the bathroom shortly after he has used it and was not particularly flabbergasted by the smell.

It’s incredibly unpleasant for me, embarrassing for him, and is taking its toll on my sheets. But more than anything, I am really worried that there is something seriously wrong with him. I’ve suggested that he mention it to his doctor, but he’s too embarrassed to.

Do you think there is reason for me to worry, or do I just have an overly sensitive nose?