I would also try to get him to have more daytime naps as he does seem to be overtired (and I bet is quite grumpy/prone to tantrums) and therefore have problems settling at night. The recommended amount of sleep a baby of that age should have is 15-18hrs in every 24, 10-12 of these at night and the rest during the day either as two naps or one long one.
Is he in a routine which you stick to as much as possible, the routine I had for my little girl at the age went like this.
Up at 7am, bottle of milk, 8am breakfast
play till 9:00 then nap untill 11:00, have a snack
1pm dinner, play till 2pm , then sleep till 4pm,
have a snack, then have tea 5pm, play for 1/2hr till bathtime at 6:00, have bottle of milk, brush teeth, go to bed around 7pm.
The times were not always exact, but always within about 15mins once we got the routine going. Sometimes we had to change because of going away, seeing family, days out etc, but during the week we got back into it pretty easily.
I found that the better the daytime naps were the better nighttime sleep became and the longer she slept, so we worked on this first (+ we seemed to have more patience during the day than last thing at night). I also made sure she always went in her cot for all sleeping (awake) and got things like blackout curtains which helped.