I have low-t level(400 ng/dl) and have been struggling to gain muscle.Recently I was down with viral fever and lost almost 10kgs of "muscle".I lost most of the weight from upper body.Now I am trying to gain weight. Someone adviced to take mass gainer which will provide high carb and protein to bulk up initially.I go to gym everyday.I had chubby cheeks,but now I have narrow bony shoulders, sunken cheeks and eyes.My waist is 36" and chest is 34".How do I gain upper body muscle in around 3 months?