Need Advice for Daycare Issue

I currently have a one-year-old and I work at the daycare he attends. Last week my son came home with three bites that were pretty bad (no broken skin) and scratches all over his face and neck. When I called my supervisor to ask if anyone had any idea what had happened, out of the 5 people that were in there with him that day, no one had seen anything happen and no one even knew they were there. As a side note my son is pretty whiney and even if my husband "fake chews" on his feet or fingers he cries. So I know he was screaming when all this happened. Yesterday he came home with another bite (very visible on the outter wrist) so I called again, and again no one had any clue. We're obviously very upset. Not because he was bitten, because let's be real, it's going to happen at that age sometimes. But because obviously no one is watching them. I'm at a loss what to do. I feel like as an employee I'm backed against a wall, and my husband is giving them one more chance before he reports them and he wants me to quit. I don't want to over react but I also don't want my son to be left alone to get hurt all the time.