Maybe processed food with MSG and High fructose syrup. Doctors I have had in the past would go hrumpf when I mentioned I could not have any. Some even said that vitamins would not help yet when I stopped eating foods with that stuff in it and took more then the recommended vitamin D and Iron then I was not tired but as soon as I eat anything with that MSG and High fructose syrup in it I get tired. The kind of tired that you do not want to do anything, even sleep.
There are so many things that can make you miserable. It could be foods your body reacts to, it could be an imbalance in your gut flora, could be disease, etc. I was miserable for about a decade-it was my thyroid as I have Graves Disease. Thankfully there is a test for it and treatment. I feel so much better.
A doctor friend of ours is convinced that diet and gut balance is the key to health. He said the total time spent on nutrition and health in med school was one day in one class. That’s it-one day. No wonder they get annoyed when patients believe foods can exacerbate or heal a problem. They essentially have no training on nutrition and health issues.