Sorry to hear about your loss.
My 3 years old black aro had faced same way with your black aro...his didn't eat anything and finally just passed away within a week.
When i removed his body, it had some blood coming from his ass too. What I suspect is the foods that i used to feed it, the food might be polluted and i didn't realized. After he ate the food, he might get internal organ infection and internal bleeding...