Sick dog:( (tw throw up)

My dog is sick and has a tummy ache. this morning he threw up yellow so i didn’t feed him breakfast, and i’m a college student so i wasn’t paying him much attention throughout the day because i was doing school work. later on i fed him dinner and he didn’t eat it. all he has done today was sleep and when he was up he would be trying to find new places to sit or be extremely clingy by sitting on me. about 10 mins ago i heard him start to throw up so i grabbed something to catch it in and it was red!! he has not drank any water all day and i’m starting to get really worried. can someone help me or give me advice on what to do please!!? it looks like the red specs is blood