What Causes Nausea And Lack Of Appetite After Taking Wysolone For Nuro Retinitis?

Hi, I am Yogish, Male 42 year old, 5ft 4in, 65kg. Recently, I had Nuro retinities (lost complete vision in right eye), and the doctor suggested few medicines, It contained Wysolone 60mg. Had it for 2 weeks and gradually reduced (per week) it till 5mg (took for more than 3 months). now the vision is back by 80%. But I have few other issues... I feel drowsy, No interest in any activity, Not interested in food etc (something similar to Depression)... To overcome this, I do morning walk/exercise. But not much use. Please suggest what to do? Will it come down after sometime?