OK abit of an update:
My wife had company shutdown till 1st Jan 2014 and for the past 2 weeks, she had been taking care of him at home with my mom who occasionally come over to help.
We notice that for the past few days, his behavour change again:
1) He seemed to have eye contact with us more often. The willingness to interact with us is there. When we wake up in the morning he would give us a big smile like he's happy to see us. Calling him my name will get his attention. If I come in the room, he will look at us. Playing with him will get his full attention.
2) His cheerfulness is back to normal. Although he still no longer smiles at strangers like during 4th month, he will steal an occasional smile if strangers try to talk to him.
3) He seemed to be less crankier.
All this concludes my suspicion. That the infantcare we put him up, does have an impact to his behavour. Now we are imagining him being lonely in the childcare will little interaction, that's why his initial behavour change to one being introvert and refusing eye contact.
Now we are wondering if we should continue with the infactcare, perhaps he is still to young for infantcare and the best age is still childcare when they are mobile and will not be left alone. We will monitor the situation for now.. If no choice, we may need to make sacrifices to care to him ourselves.