I Had A Significant Brain Injury 3 Years Ago. Since

I had a significant brain injury 3 years ago. Since the accident, I am never hungry, I'm always significantly tired, I have problems going to sleep, and NO libido. What may causing this? P.S. I am NOT depressed, I have NO anxiety, no stress and I'm not sad. I tell doctors this yet they want me to try antidpressents/anxiety medication, which NEVER helps and the problems are still there.