When he is throwing a temper tantrum and you pick him up... Bear hug him with his arms to his side.
One thing I do is immediately sit down to hold them if they are pitching a fit... (Hey, they wiggle and kick and if I am sitting down I can't drop them.) Yes, I have even sat down in the aisle at walmart. :-) And I whisper to them. They realize you are saying something (even if its your grocerylist) and quiet down trying to hear you. Muttering and whispering are different. Speak legibly, but softly. And right by their head... Yes they may try a headbutt...
Try it at home first to see if it may work for your guy...
And I just want to let you know that I have 3 kids... When I see a child throwing a fit in a store or anywhere I have NEVER thought " what a bad parent". I watch the parents reaction... There has been about 2 times I have ever been able to say "whoa" about a parents reaction to a kids tantrum.
Stay calm, not yelling back at your kids, not threatening with things you don't follow thru with(i'm gonna take that away from you if you don't stop... I mean it.... stop it now or i'll take it away.... One .... Two,..... three... I said now... stop it.... stop it I said... shhh.... quiet... wait till we get home.... hush now.... fine,here, have an icecream. ---- Not only does the kid get what he wants (ice cream) but also gets to keep what he had wanted before) smile and say things like "we don't need that crying, screaming, yelling, spitting, etc..." as you continue on with your errand...
If you have to leave the store until they calm down...
When I see a child pitching a fit I usually think something like "poor parent... I remember that stage. Stay strong mom and dad! It will pass"
Encourage him to use his words.
when he's hitting, kneel down to his level, hold his arms down and tell him softly but firmly " I know you are angry but we do not hit people..." Maybe get him one of those punching bags that you can take him to and tell him if your mad about something hit this Instead of me.
He understands more than we know, but just can't express himself yet...And that is agrevating all in its self.
Keep strong, stay consistant, and remember... There are many of us out there that are and have been in the same boat. Not all the looks are sneers... Some are encouraging!!!