Jac,
It's a horrible feeling isn't it:hugs:, my DD has been biting at daycare for a while but thankfully it seems to have stopped (nothing in over 3 weeks) but she was averaging two victims a day at one stage.
It was hard for me to discipline her as she only did the behaviour at daycare but I asked the girls to tell her, "that it is not ok to bite", that "biting hurts", and she was moved from the group where she was playing for a few minutes of timeout I also asked the girls to give her a teething ring when she bites and tell her to "bite this if you need to bite". my DD was a little older than your son( she started biting at 17mths) but in theory the principals are the same. I think she has become a lot better as her teeth settled and more so since her language has improved, I wish you luck