J.S.
Hello K.. My son has high-functioning autism but you wouldn't know it to look at him. Here's my thoughts:
--beating his head -- this is a sensory-seeking behavior...he's looking to "feel". Your son should begin Occupational Therapy soon, The earlier sensory behaviors are addressed the better the outcome.
--rocking -- this is a "stim" -- stimulating behavior -- which is a child-directed way to calm himself. Repetitive movement is a classic sign of autism.
--plays well with others -- my son plays well with others when he is not dealing with sensory issues. Not all autistic children avoid peer interaction, some want to play with others and do try to control the other kids' play (so there are less unpredictability -- autistic children do not like "monkey wrenches", they tend to NEED the known and don't like unexpected action.
--Aspergers or high-functioning autistic children have average or above average intelligence. It's a common misconception that all autistic children have learning disabilities. My son was counting to 100 and reading board books at 3 -- he's not learning disabled, just needs the right environment.
Seriously....call some pediatric occupational therapists in your area...this is critical. Your son has sensory-seeking behavior which signals something is neurologically wrong. It's treatable -- please have hope that with therapy, all will soon be bright. Autism (Aspberger's etc.,) is not curable but it definitely is treatable. Seeing the difference in my son (who sounds a lot like your son) at age 6 from 2 1/2, you wouldn't know it was the same child. Seriously, occupational therapy works wonders and helps the child find the tools to deal with their behaviors. Children know/feel when something isn't right, it's up to us as parents to help them to help themselves to right the wrong feelings they have. Best wishes.