Hello, and thanks for your medical question on E Health Forum.
From the history provided, it seems that your child could be having low blood cell counts causing anemia. This could be the cause of her symptoms of fatigue, lethargy, etc.
The other causes could be infections too.
She may need evaluation by a pediatrician for proper assessment of her HIV viral loads and initiate appropriate anti retroviral therapy if not already started and treatment of her anemia or related infections.
A physical examination and assessment will also help to grade her mental development too.
I hope you find the information here helpful.