Cat vomiting, not eating or drinking.

Question
First let me thank you in advance for your time.  I have a 3 year old DSH orange tiger. He is a big boy, and normally very active. He spent most of the day Yesterday (Sun.) vomiting, not eating or drinking. he is lethargic but pacing back and forth. he doesn't want to jump onto or off of furniture. Also there is a low grumbling noise he is making and he keeps Licking his lips like an animal would do if you put peanut butter in their mouth. He seems to go to the litter box but nothing comes out. early this morning (4am) I got him to eat about a teaspoon of baby food and he started drinking some, but it all seems to come back out a half hour later. It is 7pm now, and I have not seen him eat or drink since I got home at 2:30pm. I have read so many different things that could be causing it, (constipation, pancreatitis, ingestion of something bad) I am not sure what to do to help him. I had a plumber here Saturday who used some chemicals in the bathroom, but I thought they had all been properly flushed down drains, I suppose it is possible that he got a small amount although I didn't see him in that area. I am on a pretty fixed income and can't afford a vet visit unless it is absolutely dire. Are there things I can try to alleviate his discomfort and see if he improves or things I can give him that will aid in hydration and help if it's constipation? I felt his belly today and it feels really hard (although thin) and he grumbles when I do that. any help you can give would be greatly appreciated.

Answer
Get your kitty to a vet IMMEDIATELY!!!!!!!!!!! Do not wait one more second. He probably has a urinary obstruction and could die if he is not  unblocked immediately. There is no time to waste with this emergency. Don't even finish reading this answer. GO NOW!!!!!!
Dr. G.