whats wrong with my dog?

hi i got my dog about a month ago and he has been fine until now he's recently been trying to make himself sick and also trying to eat grass and i have no idea why, he also isn't settling at night its just a recent thing and the only thing thats changed is weve stopped giving him joint care, could that be the problem or is there something i could be doing wrong?? please help! wb sam

Has he had a vet exam since he started doing this?