Crancky fidgety 2 year old boy. Ls help!

My son is 2 years  1 month old. He is crancky and fidgety most of time. Without any reason he keep shouting throwing things in very little matter. But last 12-15 days he becomes more fidgety. Obstinate. He didn't eat even one chapati in a day. Also his weight is low only 12kg. When I say to eat he shout cry and run. Any how he didn't eat as required. He is hyper active. . I had  gone to doctor to increase his appetite. They given some syrup for him to increase but when syrup finish. He return to his normal routine . I know that he live hungry but don't understand why he didn't eat to overcome hunger. He only torture his mother. Whenever he she her start crying. Asking for breast milk. If not shout cry for minutes . In night he cry don't eat food while sleeping he keep sucking breatmilk . So his mother is also becoming sick. BCz she can't sleep well in night to. He makes our life hell. 😏. We both are helpless before him. Any medicine or anything to keep him calm first. pl ls help