Does Jaykob use dummies?
Another trick I use is to put Aidyns dummies all in the freezer... he loves frozen dummies - will usually stop the crying instantly. I have to swap them over every few minutes though, so he always has a cold one, but sometimes this is enough to calm him down and get him off to sleep.
Or you could try giving him a bottle of icy water to suck/chew on?