It sounds like your little boy has OCD. I would have him tested. I wish you the best with your son.
It sure does sound like OCD. Take him to a phyciatrist, one that works with children. It may seem impossilbe but try to be patient its not his fault.At an ealy age my son was deathly afraid of germs and he grew out of it. So the best of luck to you !!!
Another disorder this behaviour 'might' fall under is autism. Children with autism can show alot of rigid and ritualistic behaviour and any deviation from their routines will cause them to have a tantrum. Go to the autism forum page and click on the Health Page icon on the top right hand corner of the page. I have posted the DSM IV diagnostic criteria for autism and have asked parents to post examples of their child's behaviour so that parents can see the behaviour that the professionals are looking for that meets the diagnostic criteria. If that criteria looks like it could fit your child, then you need to have a multi-disciplinary team evaluation through your GP.
The rocking could be a sensory thing, are there any other sensory issues you suspect. Is he over or under sensitive to things. Is he okay having his hair cut/crushed, or teeth brushed, nails cut etc. Does he seek movement all the time, appear to have co-ordination problems or appear clumsy?
Does he have any speech disorder or delay?
My son, who is 9, was diagnosed with ADHD 1 1/2 years ago...then I was diagnosed about 6 months later. I urge you to seek out a councelor to help you navigate this terrain.
What I have found is that the effects of adhd are far-reaching...the stress can be unbelievable which in turn cause additional negative behaviors...such as the head banging. No, of course it doesn't seem like a normal response to stress, but you are dealing with a 3 year old with a ton of stimulation in his head.
I found the fact that I have add extremely helpful in understanding my son and his behavior. To me, having add is like being in a large empty room with speakers blaring in each corner and each speaker is playing something different, it's constant and never ending...which speaker do you listen to? What is that one playing? Is that one better? What if something important is on that one? Then, when you need relief from all that noise, there isn't any. Anybody would want to bang their head to get relief.
A counselor can shed light on all of that. A counselor can also do more testing to determine if your son does have a touch of OCD and to make sure that he is ADHD rather than autistic. A counselor can also advise the parents and help navigate school issues.
I have two teen age children who were diagnosed one ADD and the other ADHD in grade school. The behaviours you describe are none that I ever saw in either of mine. My oldest child with ADD hates change and the slightest thing could throw her into a tantrum but the other things you describe don't fit into what I commonly read about ADD/ADHD. Please follow up with a child psychiatrist. It does sound like something from the autistic spectrum just based on the little studying I have done on the disorder, I thought my 5 yr old might have some problems there. After seeing a specialist with him it was determined there wasn't an autism disorder but she had me removed milk and gluten products and there has been a big difference. Best wishes to you, but please, I wouldn't just settle on that ADHD diagnosis. Please get a second opinion.