My Husband Has Orange Liquid With The Consistency Of Water

My husband has orange liquid with the consistency of water dripping from his nose. At first it was yellower and now it's orange. He did hit his head against the wall about 3 or 4 times within a few hours accidentally yesterday, but there are no other symptoms. He had a cold a few days ago but according to him that has gone away.

I read online that it could be a sinus infection, but other sources claimed it could be a leak with fluid from the brain coming out. When should we be concerned?