Decision Time?

So, Willie has been sick most of the weekend again and has me quite disturbed. He had just been in his bed all weekend long and has not got out of his bed but once today. He has not eaten since Friday. Brandon cooked him some rice this afternoon but he had no interest. He started going downhill on Saturday morning, puked a few times and a number of runny poops. At one point yesterday he puked, pooped and had a seizure all at the same time than decided to just lay in the hall for a while. I eventually had to pick him up and put him in his bed. Today, he got up once to go outside on his own but other than that has not even had much to drink today. I told Brandon that we needed to have a serious discussion on how to proceed, but who wants to have that discussion. Brandon seems to think he will get better but I'm less optimistic. It bothers me to think he is feeling so poorly but it also bothers me to think he could get better. How do you make this decision??? I been joking with him that if he doesn't perk up he is going to get "the needle". But seriously, I can't even think about it without tearing up a little bit. I guess I'll give him a few more days and see how he does, but I'm certainly going to call the vet tomorrow to discuss. How do you know when it is the beginning of the end or just a bug?!?!? This sucks!