is this autism

i have a son who was born in march 2008,he is a very active kid,but have a very low appetite and also a picky eater.Recently we traveled to our native and he had diarrhea,the docs there gave him injection.Then the very next day we took him to pediatrician and my son started crying so he said he might have autism.I never doubted that because he is very social,interacts and loves and shares his toys.He started talking quite early around a year he started calling dad and now he makes few words knows his alphabets,numbers,even says that A says apple and so on...we have 3 languages so at times he gets confused and blabbers i am not sure if its normal,at times i understand him but people from outside doesn't.I am just concerned because he doesn't take medcine so i have to always mix with milk is it a behaviour of autistic kid.I raised this to our  pediatrician in US whom my son has been going to but she said she is very positive that he is not autistic.But i am very worried about this.He also gets repeated ear infections especially in the winters. and he does have frequent colds,,should i be concerned,

[bon_monty]

I cant see how a dr can make a diagnoses of autism on the fact that he cried and is a picky eater??!! If your concerned grab some books about autism and see if your son fits with any signs or symptoms. If he seems very social, engages in conversations, shares his toys, plays with the toys (ie: doesnt line them up or just watch the wheels going around), can pretend play with the toys, can move from toy to toy or activity to activity with ease, can handle daily routines being different (not exactly the same way) such as breakfast, shower/bath, brushing teeth, getting dressed, etc. Then he wont be autistic. Children with autism struggle with these things (and many more) everyday.