I had a similar thing happen. Got a concussion in July, made continual good progress (some setbacks but usually explainable), and then had terrible PCS symptoms beginning in October due to a cold.

It was the impetus for me to seek actual treatment. I'd only been seen in the ER/Urgent Care facilities during the initial few weeks, never by a specialist. Going to specialists has resulted in treatment for some eye issues and initially some neck issues that may not have resolved on their own. If you have access to a specialist (sports medicine/neurologist, generally), then this might be a good thing to check out to make sure there aren't lingering problems/address any problems that they do find. You would likely need a referral from your primary care doctor/an ER. I hadn't reached normal again, so you likely don't have as many complications and may not have any at all, but it may be worth getting checked out, especially if this second round takes awhile to recover from or it happens again.