I am a firm believer in traing good sleep habits during the day. My daughter went through about 2 weeks of this behavior when she was 2 months old. I would do whatever it took at night to keep her happy, then I started in the day time to make her take naps. Put him down when he starts acting grumpy and let him cry for 15 minutes, regardless of how hard he cries. After 15 minutes go get him, sooth him, and try the cereal in the bottle idea. Use about 1 tbsp per 7-8 oz bottle. (I recommednd Gerber rice ceral, it is cut the smallest and produces the least clogs) Once you've soothed and fed him, put him down again for 15 minutes. Mind you, do this at the times of day you want him to nap! My daughter is 6 month and her schdule is:
8am wake up, awake until 1030-11, naps until 1230-1, awake till about 3, sleep until 6-630, awake until about 8, down for the night.
If you can get his daytime schedule down it will drastically help his night time schedule! Plus, during the day you have more time and energy to work on things then at night when you're trying to sleep! This worked for be after 2 days. Everyone who has tried it says it worked within 5 days. I know it rips your heart out to let them cry, but go outside with a timer and enjoy some sunshine for 15 minutes, if nothing else you'll feel refreshed from the outdoors and it'll give you better energy! Also, I know the peds say children should avoid sun, if it's mild there, take that kid outside! put a hat on him and get him out where he's gotta sweat a little, 10 to 1 says he'll take a longer nap! You sleep better when you've been outside, so will he!