worried_mom,

That dose of B's is quite normal and should not be a cause of his symptoms. His symptoms are classic PCS. There is often a delay in the max level of symptoms as the brain tries to adjust to the injury. This delay can be up to 6 weeks or even 2 months.

At your son's size and weight, he should not be negatively impacted by the B's.

As MrsD said, he could need more B-12 to balance the rest. Sublingual B-12 may also help. A blood test for his B12, folate and D to see if his body is absorbing them properly.

How is his blood pressure? If it is high, the anxiety and high pulse can be related to excess adrenal reaction. This is common to PCS.

Avoiding over-stimulation is important. It just feeds the adrenal excesses.

Many of us have lived with these same symptoms. It takes time.

My best to you.