My Son Is 5 And Has Speech And Motor Delays.

My son is 5 and has speech and motor delays. I've also been told he has a underdeveloped central nervous system. He has ADHD symptoms and ODD (which is the most difficult thing in all of this) and is in OT for sensory. He hasn't responded well to any medication for ADHD symptoms or Anixety meds. He is often defiant especially on his off days which include then more physical aggression. Drs think all of his issues are tied to a bigger issue. Chromosome tests came back fine. EEG yesterday showed no seizures however did show some sharp spikes in the left frontal region. Neurologist said that it could be tons of things we may not actually figure out. Could sharp spikes cause problems sometimes?