if you are concerned you need to take hom to a developmental and behavorial pediatrician or a pediatric neurologist...they are the only ones who can truly evaluate him and give him a clinical diagnosis which is what he really needs to get all the services he would need...speech, ot, pt, play therapy, etc..a pshycologist can also evalutate him but you really should have it done by a dev/behavorial pediatrician or a pediatric neurologist, like i said they are the ones who can give a true clinical diagnosis. There are many differerent severities of autism...you can have very mild, moderate to severe...you can be diagosed, PDD-NOS, autisic, aspergers etc... these all fall under Austism Spectrum Disorders and again can be very mild to severe...if you concerned try to get him in to see either of those doctors A.S.A.P so you can get him any help that he might need...it is important to get help early as well as keep in mind alot of PDD NOS or austic kids have behaviors that will come and go...they will have a behavior or do something and then evenutally it goes away and the begin another..do a search on autism
ask his pediatrician to screen him for autism or developmental delays. Is he speaking at age level? That's a big concern many parents have at 24 months because not being able to speak is like a huge issue. Well, lots of issues are huge issues. I guess speech is one they can quantify somewhat. It sounds like he's shy or has a bit of social anxiety. My sister thought her son at one point had autism even though he was speaking well above his age level. He banged his head all the time and had some sensory issues over touching certain things with either his hands or feet, but other than that showed no other signs of autism. He is now 4 and no longer bangs his head and is growing out of some of the sensory issues. It's always good to bring up any concerns with the pediatriican and have a pediatrician that you trust won't blow your concerns off as nothing. You could also check out various web sites about autism and what the signs are.