I think we all need to take a deep breath and start again!
I believe that you said your son has a dark coloured suit? If so, he will be fine. Perhaps for the gala nights he could wear a slightly fancier shirt and definitely a tie. Maybe he'd also like the opportunity to wear a bowtie, they are not very expensive and do give the outfit a certain 'look'.
For the other evenings a smart(ish) pair of trousers, in other words no ripped denims, and a plain shirt will suffice. Ties and jackets are no longer a requirement although many men still wear these. Otherwise you can eat in the buffet.
Daywear is whatever you would normally wear.
Relax, you and your son will have a great time.