no worries lah, my bb was also similar, he is now 5.5 months old... he now still needs to 食 to fall asleep at night...in the afternoon my mother-in-law looks after him, so i guess she uses another way to fall asleep. I think it gets harder and harder for bb's to fall asleep and fall deep asleep.. they just are more sensitive of their surroundings...
it is just a stage which u have to accept... but remember , he won't be like that forever.. you can only keep him in your arms for probably 1 or 2 yr more.....and isn't it sweet when he's at your breast sucking happily..?