Some shedding is normal sa babies, lalo na kapag may oil at massage, but since it's relatively new for your son, I'd suggest checking with his pedia just to make sure everything's okay, could be normal hair cycle, diet, or something else na easy to address! A few of us noticed din na pag mabigat ang massage or pag manipis pa lang ang baby hair, mas visible ang fallout, pero the fact na lately lang ito naging ganyan makes it worth a quick doctor visit para you can have peace of mind, especially kung concerned ka na.