I'm so sorry to hear he is still having problems
I wouldn't worry about PCS yet though because he is probably still healing from his concussion. My neuropsych goes by 1 month then 3 months, then 6, then 1 year then 2 years as being recovery goals. If he isn't recovered by the one month then he probably will be by the 3 months statistically. The further along you go the longer it takes and the statistics drop.
I couldn't imagine letting my son play hockey again. I would feel forever guilt ridden if another concussion occurred with any permanent damage. In hockey it seems it's not "if" it's "when" another concussion occurs. You have to decide what you think is best though.
If he's still dizzy perhaps he would benefit from vestibular rehab. This is something he can get into fairly quickly without having to wait 4 months to see a specialist. There are dizziness tests they can do to see when he is no longer dizzy and ready to go back to activities.
As far as eye testing goes, there's very little in Canada that compares to the NORA examines that everyone talks about on here. I found a couple in my province but they are an hour away at least and over $600 for the 2 hours of testing. I'm going to do it if I can't get a referral to a neuro ophthalmologist in two weeks.
That is who you need a referral to is a neuro ophthalmologist but again there's very few of them and they are many months to see. Maybe just waiting a couple more weeks will be enough. Keep him calm and resting when he's not at school.
One thing I read was to be careful not to let your anxiety go onto him. I'm sure you're not but I just wanted to mention to be careful that he doesn't overhear you talking to someone or saying that you're worried he won't get better because hearing that may make him anxious and then not get better.
Good luck to you! I hope he just needs some more time to rest and then he'll be fine again. He does have a lot on his side like age, gender, number of concussions, etc.
I hope you're having a better day today!