Suggest Treatment For Stomach Pain And Constipation

my son who is 9 years old has been complaining about stomach aches. This started three weeks ago after he got braces. We gave him tylenol for a couple days after the braces were put on as he was in significant pain. We stopped the tylenol after two days. About three days later he ended up constipated and had significant stomach pain. we had him checked out by a doctor and he was constipated. Over about a week his constipation seemed to be the cause of cramping and stomach pain. It took about four or five days for the constipation to subside and he had pains persistently over those days. He slept fine at night but he complained of pain mysteriously when it was time for school. He ended up missing a week of school. Last week he made it to school but a couple evenings he complained a couple times about stomach pain but he made it to school and seemed to function ok. He had a coupe episodes in the past three days complaining about stomach pain but wehad him lay down a few minutes and he would seem to be fine. Now tonight he complained significantly about stomach pain again crying. This was over about a three hour period and then it subsided tonight right before bedtime. He continues to sleep through the night without episodes. Any thoughts