i agree with the post before mine. try fruits and juices. not that he is constipated, he's just having a harder time and could easily become constipated. but don't overdo the fruits and/or juice or the opposite could easily happen as well! so get him going normally again, do the juices and stuff for a few days and then add some fiber stuff as well, wheat germ can be put on tons of stuff and they love it! and some wheat cereal (like malt-o-meal or grits and stuff). this stuff you could even mix some juice in and get it all over with at once!