All children need sensory input, and some children need it more then others. Sensory input helps the neurons in our brains connect and if they don't connect properly our brains can't interpret signals correctly. This is why autistic children are known for banging their heads, spinning, and the like. It's to get more sensory input.
I didn't know that my oldest daughter had sensory problems and she cried all the time as a baby (really, ALL the time, especially at night when it was time to go to sleep, and when we were in stores.) She didn't like swings and sudden movements and sounds scared her. As she got older she started banging her head (I'm sure she would have done so sooner if she had the motor skill ability.)
A book that helped me understand what she was going through is The Out of Sync Child. It explains why everyone needs a good sensory diet and how to tell if you have a child that needs extra help in the sensory areas and how to tell what they are. There's a companion book of activities to do to help your child regulate his brain.
If he DOES have sensory problems, it COULD indicate other problems such as ADD/ADHD or autism. Many parents don't notice autism in their children until around 13---15 months and it's been questioned wither the vaccines given may be triggering the autism symptoms or making previously unoticed autism worse (such as loss of speech.)
Don'd be afraid of the word autism though! A lot of children have sensory problems that are not autistic. And therapies and diets can help autistic children tremendously. My oldest has Asperger Syndrome, a form of autism that does not have language delay. My next two have classic autism (didn't notice any traits until after their 1 year vaccines.) But the gluten free diet and sensory activities have made a huge difference in their development.
DO get the book, your library may have it or be able to get it from an interlibrary loan. If you notice other concerning traits talk to your doctor. You can also contact ECI for an evaluation. The ECI in my area has an occupational therapist that evaluated my daughter for sensory integration dysfunction and then showed me things to do to help her. Evaluation is always free and therapy is free to cheap depending on your income level.
Feel free to write to me. :)
S., mom to 5!