My 2 year old fell and hit the back of have head , he immediately got a large knot. how long do i need to watch him and for what symptoms ?

Loss of conscious ?: Any 2yo that is not knocked out by a fall can usually be monitored at home. It is common to get a bump, vomit x1, & get a headache. Let him nap/sleep on a normal schedule and check him with a flashlight during sleep.If the kid lost consciousness, vomits in his sleep or vomits repeatedly, you need to take him in.

Over the next 24 hrs: If your son starts vomiting, is more irritable not using limbs properly, not easily awakened take him to the er.