C.G.
my daughter had a really flat head also at that age. i remember really being worried about it. but she grew out of it when she started rolling more and falling asleep more on her stomach after 6 months.
i have seen children with the helmet, but i think it has to be pretty extreme for that. i am assuming that if you are going to childrens that maybe your pediatrician was concerned? or is that where your pediatrician is? but i think at 6months they are just really learning to roll over more and play on their tummys more, so he'll probably grow out of it. good luck.