I've posted this in behaviour/development as well, not sure if it applies here so apologies in advance if it doesn't.
DS is 4 and I am beginning to wonder if he may have ADHD.
He is constantly fidgeting, talking, starting things and not finishing. He will not listen to instructions if it is something he finds 'boooring' even for things like looking for cars before crossing the road. I seem to spend my life repeating myself for every little thing.
He has a very quick temper if he feels he cannot, or does not want to, do something, even something as small as picking his clothes up or putting together train tracks. Sometimes he is easy to calm down/encourage but others he will stamp off and whatever the task was, he will declare it 'rubbish'. Tears are very frequent but then 2 mintues later, he is fine and doing something else.
He is contantly running or stamping or climbing over the furniture despite being told over and over. Any punishment does not dis-courage him from doing <insert behaviour>, he will simply take the punishment and then carry on, usually to repeat the same thing straight away. I have tried only praising the good behaviour and ignoring the bad to the same result. I have tried withdrawing from him when he is behaving badly but again the same result.
That all being said, he really is a kind, helpful, loving boy. He is often like a little puppy with me and I get loads of kisses and cuddles, he will lay with his head in my lap and clamber all over me (hence the puppy comment), he tells me he loves me several times a day - and then he charges off again! lol
He will concentrate on something that interests him (at the minute space) and will watch a 20 minute video or listen to a book about it.
Sorry for the post of epic proportions but I don't know if I'm way off the mark and this is all 'normal' 4 y/o stuff or not
Also to add to that, I have been called into DS's nursery due to the fact that he will not sit still, and also during an open morning, the teacher made comments about how he will fixate on a paticular activity to the exclusion of all others and that we need to work on encouraging him to play with different things instead of his current favourite
tally 4 is still very young to be sure. My son is almost 10 and got a dx of ADHD when he was 7. School flagged up problems when he was year 1, but they had been there the moment he could walk. Sounds similar to your ds but without the fixation part. My ds didn't get angry and was actually compliant as a pre-schooler. You GP may go ahead with referral, but don't be surprised of they are reluctant at this stage. Good luck