Ds has a high pain threshold when it comes to self inflicted pain, ie bouncing and crashing into things, he used to head butt the floor until his head was bleeding, scratches himself causing large sores etc, etc.
Im sure its a sensory thing. OT explained it me as being under-responsive to touch
Hyposensitivity To Touch (Under-Responsive):
__ may crave touch, needs to touch everything and everyone
__ is not aware of being touched/bumped unless done with extreme force or intensity
__ is not bothered by injuries, like cuts and bruises, and shows no distress with shots (may even say they love getting shots!)
__ may not be aware that hands or face are dirty or feel his/her nose running
__ may be self-abusive; pinching, biting, or banging his own head
__ mouths objects excessively
__ frequently hurts other children or pets while playing
__ repeatedly touches surfaces or objects that are soothing (i.e., blanket)
__ seeks out surfaces and textures that provide strong tactile feedback
__ thoroughly enjoys and seeks out messy play
__ craves vibrating or strong sensory input
__ has a preference and craving for excessively spicy, sweet, sour, or salty foods
Ds doesnt fit all of that list, as his mouth is over-responsive and nothing goes in it, apparently ds has a combination.