I'm pretty sure it's to do with his teething, he's clamped down the odd time before but over the last week has bitten lots, and today especially he has bitten loads at every feed 
Any tips on what can be done? I'm yelping when he does it (can't help it!) and following with a stern "no" and serious face, have also tried a bit of bonjela just before feeding, but it seems no deterrent. Is it just time to stop bfing?
I don't really want to stop yet, was planning on kind of letting him decide when it was time to stop, but I'm not sure how much longer I can take the chomping!