My boy is 2.5 and is very determined, physical but sweet with it. He's been headbanging since about 14 months (on the floor, walls, radiators) but this got better as his speech improved (around 2 years old).
Recently his headbanging is worse again but, this time, he's biting himself and hitting himself too. He doesn't hurt others at all, just himself.
There is always a reason for the tantrum (not wanting to share, being told he can't do something dangerous etc) but he goes from 0-100 very quickly. I make sure he's safe and can't hurt himself and leave him to it. I normally sit near him and he comes for a cuddle when he's calmed down (after a few minutes). I talk calmly to him and explain that I can see he's upset but he and do xyz because it's not safe etc etc.
He's having these epic tantrums at least 3 times a day. 3 times in a day would be classed as a good day. He's been screened for autism at 2 and came up as low risk but monitor. His speech is average (was delayed but has caught up) and his understanding is excellent.
Any help would be appreciated as it's awful seeing your child so frustrated and hurting himself (his bite marks leave bruises on his arm).