Ohhh mama, hitting head tu memang common stage at this age, tapi dia bukan sign yang dia nak tumbuh gigi atau jalan, dia tengah explore cause and effect je, especially around 9-10 months when they're getting more mobile and curious! A few of my mum friends had the same worry, tapi it's usually just their way of experimenting with how their body works, macam hitting things on high chair atau lantai. That said, if he's doing it repeatedly, very hard, or ada anything else yang tak quite right (like unusual crying atau changes in behaviour), it's worth checking dengan doctor just to be safe, okay? Don't stress yourself, this phase usually passes!