My Yorkie pup just got his first rabies and last set of boosters and deworming on Monday. It is now Friday. His symptoms started on Wednesday with diarreah

(only once)..The next day (yesterday), he started scratchy his ears and making crying noises..then a couple hours later I heard his stomach growling very loudly and he started dry heaving. This happened all while we were sleeping. So tonight, he threw up twice within 15 minutes of each other. No itchy ears noticed, though. I am just very worried he might be having a reaction to the rabies shot, or the new food I switched him too which is AAFCO approved..but I switched him about a couple weeks ago, so I'm not sure? I looked online, and the most probable cause is allergies? Not sure if I should take my baby to the vet soon or what. Please help new parents