I doubt the Prozac is intended to treat his PCS symptoms. More likely to treat anxiety and depression to allow him to relax so he can sleep better. It starts to take effect immediately but continues to increase in effect over the next 2 to 6 weeks. During this time, it is good to be watchful of him and even better, to have a professional assessing or helping you assess his mental condition. The young brain can be more reactive to SSRI's.

Having been through the thought processes symptomatic of concussion during these ages, I fully understand what can go on inside the injured mind. The Prozac can provide a good benefit as long as he is properly monitored.

What were his B-12, folate, and vit D levels?

Many doctors and labs use very wide ranges as normal. The injured brain need to be at higher levels near or even above the top of the normal range.

After my concussion in 1996, I became very sensitive to any kind of changes and toxins.

I hope you can get some useful understand of what the doctors are up to.

My best to you