I can't eat gluten, but have never heard of TMAU....what is it?

I think the important thing here is that you have a noticeable Body Odor - for what you might recognise as fishy smell another person might call it something else. This might be a sympton of toxic overload and indicate that your liver is not doing a good job of removing toxins from your body. When this is happening a different detox system in your blood and tissues can bind the toxins using sulfur containing amino acids and the bound toxins are excreted in the apocrine/sweat glands. These sulfur bound toxins have a strong odor. You can do what I think of as the 'Smell Test". Just eat several cloves of garlic and by the next day you will notice a strong, distinctive smell in your armpits.

I have gluten sensitivity and did have a strong Body Odor off and on for years. Eating gluten did not cause it but it happened most often after I ate commercially prepared food and sometimes with supplements which weren't pure. A good detox program might help a lot.