Child is more agressive. Severe tantrum!

My 2 years 8 months old child weight arround 13 kg having height around 95 cm. He is picky eater. And eat healthy food only when he watch tv or mobile. Otherwise no one can feed him healthy food. Other food he can eat easily. Also he becomes agressive in small things . He would be playing well in good manner. And sudden any one say not . Then he lies on back and slowly he hit his head with both hands If we ignore than he increase speed. Still ignore he hit head on floor slowly bcz he knows he would hurt. Still we ignores then he start giving flying kicks lying on back, he keeps his both leg vertical to floor  and hit with force doing them down. And shout very sharp voice which can cause hear loss too. Also he rub is neck backwards by fixing his leg on floor move upper body back side with force using  head . Sometimes he turns his neck left right and rub towards sofa while sitting on floor. I want remidies to stay him calm. I think only medicine will work for sudden severe tantrum