1. Did he had to much nap in the day time? If so, cut back.
2. Touch around his tummy area. Is it harden? If so, he might be bloated. Apply Huand Xiang Hua Ru Yi You
3. Teething? dont't apply jin feng san. That's not for teething. Go to guardian pharmacy and get a proper teething gel. quite cheap.
4. Did he has his milk before he sleeps? If so, test the temp. Sometimes too cold baby can't sleep.
5. Did he watch anything before putting him to bed? If so, cut back at least an hour and half.
6. Was his day occupied? If not, play with him more to make him tired.
7. If all the above fails, it's probably he wants to get close to you and test the boundaries to see if you will let him sleep with you. You've got to be firm with him and tell him it's late and it's time to go to bed. Placed him in his crib and dont't play with him. Of course you will have to peek to watch his safety. Once his realized he is not getting your attention, he will just fall back to sleep. that's what happened with my baby. =)