Wow I can't imagine being 15 and having a problem like this. Your in school all day and kids do have there own unique way of making you feel horrible. I'm so sorry your going through this at your young age.
Have you been able to get tested for TMAU? I know there's a place you can send your urine sample to and they'll test it. Have you tried any of the diets or supplements that work for TMAU people? If you have medical insurance, you might be able to test to see if your Celiac or gluten sensitive, which can also cause this problem.