Headcrashing toddler and his wrath

Hi mommies, I need help about toddler tantrum. It started about 5days ago when my cheerful little boy turned into a self-destructive machine when nothing is his way. As soon as he is not happy, he’ll bang his head on the floor, the crib or crash his head against mine. And because of this, we can’t sleep train him. He is now 14.5months old. Will be so grateful if you can share your experience(s) with head-crashing toddler(s). Would be very interested to learn methods of calming him down and putting a stop to this behaviour. TIA!