Should i be worried??

i have a 16 weeks old dogue de bordeaux, he is teething at the moment and chews everything but last week he vomited 3 times it was full of twigs and gr, he hasnt gone off his food and eats 4 meals a day and plays and runs around all day, im just a bit worried why is he doing this? is it beacuse he is teething thats why he is eating twigs and gr or is it something serious please help