Stolen baby!?!

I am biracial( African American and White) and my husband is German/  Portuguese, so as white as they come. Our 9 month old son took almost  all of his features from his father. Up until now I've gotten used to the shock and comments when people see a blond hair and blue eyed child with a black mother. I've gotten everything from " are you the nanny?" to " what agency did you adopt through?" But the other day a woman actually called security in Marshalls because she thought I was trying to leave with someones child...the month before, a new worker at my sons day care didn't believe I was his mother and asked I provide PROOF that he was my son before I took him home. I'm not even sure how to handle these situations anymore. I'm starting to feel anxious about how my son looks and I'm not even sure how to address or fix the issues....help? I need some advice