I am glad OP's son looks to be well and seems to have had a transient reaction to his vaccines.
I find the dismissal of any person who expressed any anxiety about vaccines or mentions that they can cause reactions as hysterical anti-vaxxers very frustrating.
Yes at a population level vaccines have been a completely fantastic public health success and have prevented the deaths of millions of people globally from diseases that terrified people just a few generations ago.
This does not mean that some children, presumably for reasons of their immune system functioning and/or genetic makeup, don't have severe reactions to vaccines which can be as bad as or even worse than the illness they were being vaccinated against. I know this because, as a previously happy go lucky vaxxer who took every vaccine going for my kids and even paid for additional vaccines, one of my sons has now had two severe reactions to vaccines, one of which came close to killing him.
He developed severe immune thrombocytopenic purpura after a flu vaccine (not nose squirt) which left him with zero platelets and bleeding from the nose, mouth and into his skin. Any blow to the head would have killed him. It took him a year to recover fully.
He then developed pericarditis after his second COVID vaccine (Pfizer). His GP advised no more COVID vaccines (he was given them as there is a family member who is immune suppressed).
I don't worry about my other children having any vaccine they are offered, but for this son from now on the illness being vaccinated against would have to be very severe indeed for me to grant that permission, and I will ensure into adulthood that he is aware that he appears to often mount very strong reactions to vaccines.
Dismissing that 77 people have been so damaged by COVID vaccines and able to prove conclusively enough that it was the vaccine that caused the damage so as to get the payout feels very callous if your child, or brother, or parent or spouse is one of those who has experienced a life changing reaction.
Of course at a population level vaccines are a wonderful, wonderful thing. At an individual level, particularly where people have had a previous significant reaction, this can be more equivocal, and whilst severe reactions are thankfully very rare, they do happen.
My son has been that one in a million kid who has had a huge reaction twice now. When that happens to you, it causes you to re evaluate truths you have always held as certain, like that only hysterical anti-vaxxers worry about vaccinating and that of course everyone should have every jab going. I hope you never see it from this side.