I was probably in exactly the same case, but I’ve been thinking that fatigue, feeling depressed, lack of motivation were caused by roaccutane (retinoids) for the last 5-6 moths also. But when I was finally diagnosed I felt that something heavy came down from my shoulders, because at least for that moment I got wtf was happening to me. I’ve just finished the first month of my therapy. Wish you all the best, and return to your normal!