Sound like your hot spot isn't hot enough. I would just increase the hot spot to 100-110 and give him some time. It takes some babies a week or two to fully adjust to a few encloscure. Its good he ate and was checking out everything. Make sure you mist him and keep him hydrated. If he doesn't poo after you increase the heat I would give him a nice soak in warm water no higher then his shoulders. Usually always works
Good luck!
-Amy