Well right now your son is sick, so until his illness has passed completely (2 weeks at least) instituting new strategies is only going to make it hard on both of you. So let him recover.
Second, I looked at you post history and something like 7 out of 10 questions deal with your son being stubborn and throwing fits... so I wouldn't call this behavior "recent" but rather ongoing.
I will also echo what a lot of moms already advised: stop trying to be his friend and "understanding" him and start being a parent. Less talk and more action. I don't believe in "tough love" (certainly not at this age) so I don't advocate that you need to hit him with some disciplinary hammer. But kids NEED boundaries. Not having boundaries is confusing to them and causes a lot of emotional upset and insecurity in children.
What do you DO when your child acts inappropriate? Why is it ok for him to hit or kick anything when he is frustrated? How is that teaching him that his way to deal with frustration is not acceptable? Would you like to live with an adult that punches holes in the walls when s/he doesn't get what s/he wants? I don't think so.
Start showing him what acceptable behavior is by modeling it and acting on it. Give him chances to be successful and then praise him:
Throwing a fit at the dinner table... you must not be hungry, please go to your room so the rest of the family can eat in peace and quiet. But when he calms down and comes back to the table praise him for gaining composure and thank him for acting nicely.
You are calling me to your room? Once you stop crying and raging I will come and give you a hug and we can talk. Then go and do it and tell him how proud you are that he calmed himself down, because it is so hard to talk to someone who is screaming.
None of this is unfair or cruel, but it will show your child where the limits of socially acceptable behavior are. And that raging and crying doesn't get him what he wants, but behaving nicely will.
Kids his age are still acquiring the skills to overcome frustration in a socially acceptable manner. At the same time that you stop letting his tantrums rule your life, you can also teach him some coping skills. Raging on in your room hitting and kicking the furniture is NOT a coping skill IMO... maybe some people think differently, but I'm not buying it.
I used to talk to DD after the tantrum has passed (she is 6 now so not really happening a lot at this point - maybe once a year) and we went over how she was feeling and what she can do instead of yelling and screaming (count to five, take deep breaths is our strategy) when she gets the frustrated feeling. And we practice this by role playing and reminding her of taking a deep breath for example in a situation that has the potential to escalate. Also ask HIM what he thinks would be an acceptable way to act next time the situation comes up.
Whatever method you choose - it needs to be clear to him that throwing a tantrum is NOT getting him what he wants. You don't have to be mean or strict or over the top, but you also cannot give in.
Good luck.