My 5 year old boy has been on blue buffalo lamb and potatoe for about 2 years but recently he started throwing up during the night 2a-3a (chunks, not foam or bile) and sometimes during the day 2p-3p. The vet believes it is due to food allergies. He suggested duck or salmon based sensitive stomach and added he preferred the brands royal cabin or hills... problem is so far as I can tell these brands don't have a duck or salmon based sensitive stomach blend (chicken only). Because I couldn't find what he suggested, I switched to blue buffalo duck and potatoe about a week ago but the throwing up hasn't stopped! Just wondering if anyone has had similar issues with their bullmastiff and interested in what diets have worked for you. For reference, we feed him around 7am and around 5pm each day from an elevated bowl. The throwing up happens probably about 3 out of every 4 days and has been going on for nearly a month. Any help would be most appreciated.