L.R.
Hi C.,
First, have the doctor rule out any illness. Next, start putting him to bed earlier, say around 6pm. Most night waking is caused by too late a bedtime. I HIGHLY recommend "Healthy Sleep Habits, Happy Child" by Dr. Marc Weissbluth for sleep training and problems. Google him and you will see how experienced he is in the area of sleep. I used his methods on my daughter from birth and she is a great sleeper. Email me if you have questions, I'm ALWAYS happy to help everyone get better quality sleep.
Sincerely,
L.