Sleep!

I dearly love my son. However, after three nights of having him wake up every two hours, I'm ready to ...I don't know! How is it that he was doing so well- sleeping up to 10 hours at a time and now is worse at night than when he was first born??? Any insight? Suggestions? Last night I broke down and gave him rice cereal before he went to sleep. Didn't help. Really, I'm at a loss here. Anyone?