First of all, keep in mind that I am unable to diagnose you because I am unable to examine you, this forum is for educational purposes.
Some of the symptoms that you describe can be found in autistic spectra disorder (more properly called pervasive developmental disorders or PDD), such as lining up the cars, poor social interactions and inflexible quirks. However, since his speech sounds relatively normal (he should have 20-70 words at this point) then he will probably fall towards the less severely affected PDD such as Asperger's syndrome. It is normal for children to explore their bodies (even poop at the time of potty training), but this should not be a recurent activity. I agree that you should have him tested by a professional (pediatric neurologist).
I hope this has been helpful.
There is some suggestion of hypersensitivity for instance dislike of haircuts. you need to be aware of things in the environment a non autistic person would not react to in order to understand the triggers for the tantrums.
I don't believe autism is in the province of neurology at all, albeit it is caused by differences in the brain, they are not the kind that are detectable by neurological investigation and a diagnosis of autism is made by reference to behaviours arising from that difference.
My son was talking at the right age except now his speech is deteriorating and now he only speaks when he is repeating something. My son screams in shopping centres again to do with over sensitive vision and hearing, he can't distiguish frontline noise with background noise so to my son the tills beeping and the people chatting all around sound so loud to him. All the colourful signs and labels and colours of peoples clothes and patterns overwhelm my son so again makes him scream in frustration. My son also lines things up. He has never played imaginitivly. He has 40 toy cars which he lines up in colour order - he started this at 18 months old - amazing but a sign of autism. My son won't play with other children, he can't even stand them near him. Not even his brother. It's great your having your son tested because the earlier you do the better outcome you will have with your son. I don't know about your son but my son has an obbsession with numbers. From the age of 12 months he could count to 20 and recognise the numbers when written down and I had never formally taught him them. He now at the age of 3 can count to 79 write his numbers and recognise them, again with no formal teaching. But he has problems like he can't feed himself properley he isn't showing any toileting awareness, is very clumsy. They are other signs you can maybe watch out for.
i have a two year old, normal toddler, EXCEPT
I have a two year old, normal toddler, EXCEPT, SHE'S STARTED EATING HER OWN POOP! Is there something wrong with her? She eats a very well rounded diet, plenty of fruits and veggies...Please help!!! Thank you so much!