Those who say paintballs cant give concussions have never taken any to the head like you have. One of my friends took a hot bounce (crappy paint that day) to the head. He had a beanie and the shot was from about 50+ feet, he still had to sit down as he went dizzy from the minor concussion.
You could wear a headband, beanie, visor (backwards obviously) or just add some sort of foam to the back of your mask. Go to a sporting goods store and look in the apparel section. You will find something.
+14 years of paintball experience.
Loves double chocolate cookies.