I Have Been Feeling Very Fatigued, Depressed, Anxious, Loss Of

I have been feeling very fatigued, depressed, anxious, loss of appetite and insomnia for weeks. I wonder if it's more than just work stress, anxiety and depression and that there may be something physically wrong with me. I was recently diagnosed as pre-diabetic and have gone off sugar, white flour, most grains and coffee. Could part of what I'm feeling be de-tox? I am 63 and many of my immediate family have died young.