DS has bitten one (on rare occassions two) kids at daycare everyday for the past two weeks. I have tried everything to get him to stop biting and nothing is working

At first I thought it was just teething. Now I think he is using it as a game and as a defense mechanism. I asked if he keeps biting the same child and they said this week that he has bitten the same kid more than once. Even though they should not have told me, they told me who it was and said that the child took a toy from DS and DS bit him. I know that so many toddlers bite but I am at my wits end

I have re-directed him and it does not work. I have told him "no bite" set him down and walked away. I have pressed my finger to his mouth and said "no bite". I have told him that it hurts. I even bought two books about biting to see if maybe (I know it is a stretch) that it will eventually sink in. I have school giving him Tylenol regularly for the pain if he is teething. I even gave them teething tabs and orajel to try anything and everything. I give him toys to chew/bite, instead of trying to bite people. He keeps biting DH and I and laughing when we tell him no. I even (gulp) spanked him the other day and while it got him to stop, I worry that he will move on to hitting because he thinks it is acceptable. HELP!!!!
Re: Biting HELP!!!
I know it will pass I just hate that he is biting every single day at school.
Why doesn't the school know how to handle this?? I am sure it is just a phase, but the school needs to work with you on being consistent to stop the biting. What about baby bitters? Not sure if they make it, but when he does bite, put something in his mouth that doesn't taste good. My parents had to do something like this for me when I was little.