I've had 4 concussions in 6 months from being headbutted and kicked in the face at work (in a group home caring for severely autistic adolescents). is it safe for me to continue working in this field or do i need to change my career to save my brain?

I would change my career if I were you! Repeated concussions take a toll. You are more likely to have migraine type headaches now as well as the risk for decreased memory and other serious long term effects.

If it is possible to change your career, do that, as soon as possible. In the interim, or as a permanent solution, wear a helmet at work. You may a consult a sports medicine doctor for the proper choice of a helmet. Wish you good health!

You describe a violent work environment, and unless you change jobs, injury potential will continue. A football helmet would help, but not clear if your employer would cooperate. Maybe you should consult with your state's Worker's Compensation Program, as this could be a more complex challenge than it appears.