toddler behavoir

Hi, i am worried about my sons behavior but im not sure if im worrying for nothing. My son is 3 and since he was about 18 - 20 months hes been a handful. At nursery he went through a stage of pulling other childrens hair and hitting them, and constant not listening, althought this imporved and he hasnt hit another child in a while, i am worried about his concentration now, he cant seem to concentrate on an activity unless hes really into it, he constantly jumps about on top of people in the house and generally doesnt listen no matter how many times you tell him something. He's quite clever and his language skills are great, i can have a full conversation with him and have been able to since he was about 2 but he uses made up words sometimes and if i dont understand what hes saying he gets really worked up about it. In nursery he constantly doesnt listen to his teachers and can be quite cheeky and shout at them. I recently took him to a tae kwon do class and he couldnt wait his turn to do things and was constantly rolling on the floor nots listening to what he was being told. he interrupts people alot and will keep shouting until you answer him. sometimes i feel like he doesnt take in what your saying to him and he will repeat a question over and over again until it seems to go in. Should i be worried? Tweet