I will say this much, without an actual laboratory and doctor confirmed test that states she has TMAU, she could be suffering from anything non-TMAU related. TMAU isn't the only condition that causes people to smell bad.
First and foremost, do "Go" to your primary care physician. Don't "assume" that you have TMAU. The power of assumption can only serve to cause more frustration. The reality of the situation is that she's going to have pay her family doc a visit, no matter how embarassing she thinks it is.
Also, doctors deal with "embarassing" conditions. Erectile dysfunction, constipation, IBS, low or lack of libdo. I'm sure Body Odor isn't going to make them flinch. They are after all "doctors." My advice? "Just do it" like Nike! Go to the doctor! Knowing is half the battle! Good luck!