2 years old toddler back side head keep.

My toddler 2 years old. Very week. 12 kg weight while in one year his weight was 10 kg. Not gaining proper weight. Apart of this. My baby head in backside keeps warm like something heating consistently. While frond head is cool even in ac . And his behaviour is not good. He is fidgety obstinate most of time. If he wants something and not given then he hit self hit forehead on floor. So I am worried that it's due to warm head that cause impulsivity and not able to stable him. It feels like he is in search of something every time. Bechaini like. In night time due to hot head I thing he took time in sleeping it takes 1-1:30 hour to make him sleep. I belong to small town and i can't move to see for costly treatment. I am worry that his head hotness cause him imbalance in daily life. What could be reason if all factors are normal. What can I give him for remain quiet and calm. Because he is implusive and restless behaviour. Suggest syrup for brain and neurological development