Hi A.,
I have two children and I know that when both my girls were younger, they would have trouble sleeping. As you mentioned, it could possibly be that your son is about to cut teeth. It could also be that he has gas, or colic. My girls experienced this. I reccomend a weak bottle of chammomile tea sweetened with a tiny bit of sugar. Not honey. Either way, chammomile will help settle an upset tummy and it also has anti-inflammatory effect on the gums and teeth. It is also a mild sedative. Plain Chammomile tea can be found at most local grocery stores, even WAL_MART. You can even fill the bottle with hot or warm water, place 1 teabag in it and let it steep for a few minutes. The point is not to make it too strong, even though it is a gentle herb. As with any herb, there is a possibility of allergic reaction so start out with very weak infusion. I do NOT recommend other blends of herbs along with the chamomile such as Celestial Seasonings "Sleepy Time Tea", because these and similar teas contain herbs that could be too potent for a little guy.
A warm bath right before bed with baby wash that has lavender or lotion that has lavender massaged into baby's skin, before bed, can also help immensely. 'Johnson's' brand baby body wash is what I used.
Well good luck, and I hope some of my advice helped. God Bless!!