It might not be autism! A good family friend of ours was like this, he would bounce between the walls down the hallway, would roll off the couch over and over, etc. Turned out he just had an overactive need for physical contact. They got him into soccer, which helped IMMENSELY and he ended up getting a full ride to JMU for it in the end. And no autism - fully functioning socially, happily married now in fact. In the meantime, for baby/toddler, you might want to ask your pediatrician about weighted vests or compression wraps? Best of luck, I’m sure it feels scary!
first it’s to early to tell if a child has autism and even if he does he’s still your baby boy,, second my son shakes his head when he’s sitting up i think he’s just learning to use his neck muscles differently, the slamming his face thing might just be fun for him my baby smacks his face on stuffed animals, blankets, pillows, me even,, a good reminder too if it’s unwanted behavior don’t show a reaction good or bad because they might do that one thing to get a reaction, sounds silly but it does work i’ve babysat and taught many kids in my short life lol just don’t listen to people about silly things you know your child they don’t
At this age it’s usually just sensory seeking and exploring their own cause and effect in the environment. If it continues past 15-17 months maybe look into it but if they are still meeting all of their milestones that’s the most important part you can use the CDC milestones tracker or the sparkler app.
My daughter does it too but her pediatrician hasnt mentioned concern about it. Babies are sensory seeking to the max. I won't worry about any neurodiversity until she's closer to 2 where we can actually get a diagnosis if needed.