It does sound like stomach bile that he's throwing up. Its hard to say because Beefy does thst from time to time when he has an upset tummy. I just give him some childrens pepto and some pedialyte. If they ever get sick I usually give them chicken broth instead of food till their tummy settles. I don't think its the cider because I give that to Georgia and Beefy a few times a week but all dogs are different so it could be possible