I think toddlers may still lack the language or impulse control to cope with their feelings. They hit without thinking about the consequences or other ways to get their needs met.
I’ve a daughter with Down Syndrome who still deals with these issues at age 7.
We make sure we don’t react emotionally, but very neutral,
Help her to verbalise her feelings,
Help her to chose better options than hitting/kicking/throwing (for example deep breathing, have a jump on the trampoline, take a sip of water)
Make her aware of her behaviour by asking was it a good choice or bad choice
Followed by helping her to say sorry and make things right

Oh gosh I wish you luck love, my son was the biter, kicker, hitter and scowler LOL It is stages not ages!!

can you get me advice from your CHN? does he go to day care? we still have a problem with our boy, mainly pushing, currently seeing a psych and being refered to parenting support groups. hows his language skills? I like the program 1, 2, 3 magic.

With hitting his head do you mean with his own hand or against the wall? if against wall id get him seen by doctor for autism, other wise most kids go through a hitting stage in toddlerhood, just make it clear it hurts and you don’t like it, and make it clear its unacceptable, put him in naughty chair or send to room or stop the fun activity you are doing or remove him away.