Passenger in MVA air bag deployed causing loss of leg function and seizure. 3 weeks later I have nonstop migraines affecting vision hearing and mood?

Sure to be migraine? Not sure these are migraines. Given there was trauma, a post concussive headache is more likely. The symptoms are a bit different, and it should be possible to sort them out. Are the legs recovering? That is the most serious part here. If so, you can probably try certain treatments for the headaches. Rest is important. See link: http://www.neurocuro.com/concussion-poll-for-everyone.
Following up?? Sounds like a high-cervical or brain injury ("whiplash" / SCIWORA or concussion), and should be getting further evaluation by a Neurologist / Traumatologist to be sure is part of the healing process (and provide meds to make it less debilitating) vs markers of a problem in need of MRI / Neurology consult / intervention / etc. If not yet, need to see a Neurologist at a L-I (or L-II) Trauma Center.