Too much crankyness irritation anger.

My 3 year old child show anger every time when bathing eating , and most of activity. Neither he eats properly. Even he takes 9 hour sound sleep in night. He keeps demanding and show anger on anything . Keeps crying for more than half an hour or more if not fulfuling his demand. All family members are very frustrated because of him. Also he irritates his cousin 1 year old sister. He pinches her put hand on her head. Specialy if we tell him to not do , he does the same and challanges us. And in this way , he always been in anger. He hurts younger cousin . Show tantrum very often . We have been exhausted  I am not able to understand why is this happening more and more from last 10-15 days. Any medicine pls recommend. His weight is 14 kg. Little bit constipated. Eats lots of dryfruits, like almond pistachios, and  baked chana  and paneer. And he eats 1-2 chapatis in noon and night. I didn't offer banana , this cause him constipation. Jiddi bahut hai sab pareshan hai.