Sick Romey

I'm really worried about Romeo, my sweet kitty. He's not well. Last week he tried to cough up a hair ball, which isn't that unusual. He's got long hair and is constantly cleaning himself..this involves a lot of licking his fur. Eventually that fur has gotta come out so he coughs a few times and bam, it come out. I thought that was what was happening last week, but after a couple of days he still hadn't got it out. Then he started to make this little kitty whining noise, dry heave, trying to cough it out but just white bile would come out. He started to look a little on the thin side and we noticed he wasn't eating or drinking much. We thought maybe he just had a really stubborn hair ball and we'd try some stuff that helps loosen in up so he could cough it out. But then on Sunday Rob noticed that Romeo's pee was almost neon yellow. This is a sign of dehydration and not good. I tried to get Romes to drink some water, which he did, but then he promptly threw it up. We tried one more day of getting him to eat or drink something, but he had no interest. He's just lying next to me, weak and sad and it breaks my heart. Rob is going to take him to the vet today so we can see what's going on with the little buddy. I'm really worried about him and can't help but cry to see him like this. It's a hard thing to understand if you're not a cat person, but Romeo is my baby in a way. I've had him since he was 4 weeks old and he's now 6 years old. He's been with me through all my good and hard times, moved houses with me, has always loved me unconditionally...I just want him to be ok. Please let him be ok.