Virus -- 3 cats lost their appetite

I have 3 indoor cats aged 4, 5, 5 years. One day I came home to find one kitty missing from the usual parade of cats wanting dinner and quite a few spots of vomit. Okay, she clearly wasn't feeling good. She moped about for 2 days then started improving. She still is eating very little compared to before. This has been 4-5 days now. Now the other two cats aren't eating much either. 
 

I took the first one to the vet and she did $150 blood work panel and found nothing. 

So two questions:

1) has anyone else encountered this?

2) Any ideas on how to get them to eat? 

OK...they canNOT go without eating for very long at all without the possibility of some serious liver issues.  I'd suggest, if all else fails, getting some syringes without needles, and some pate canned cat food.  Mix the food with warm water till it is soupy and smooth, suck it up in the syringe, stick that in a cat's cheek, and get the food in them  that way.  It will at least keep the Kittehs going until you and the vet can figure out what is going on.

Instead of water use goats milk. It has natural probiotics that help with many tummy troubles. Some people are able to find it with the regular cow milk I find the canned and powdered kind in the baking aisle. Just follow the directions for mixing with water. Good luck

So far they're eating a little, but only a fraction of normal. Man, this is so weird.  I bought some really junky dry food hoping I could persuade them and some tuna paste in a tube. They're eating a tiny bit, but not much. They're not throwing up or anything. 

Oh yes, another oddity is they seem more nervous than normal.

Update: 2 of the three have recovered somewhat. The third is still unable to keep much of anything down, but his appetite is still there.

Do they go out at all?  This almost sounds like they got into something. 

Nope. They're indoors only.

Well, they all recovered. 2 of the three had a serious lack of appetite for 2-4 days. One had a reduced appetite. 

I suppose that I must've somehow transmitted something to them, but hadn't seen any other cats in some time. The only place they could get into anything would be the garage and from time-to-time lizards get into the garage. However, they don't eat the darn things, they bring them into the house and chase them. 

What food are you feeding? Are they all eating the same foods? The first thing to do when something like this happens is throw out any food that all the cats are eating. Most of the time this is related to food, but it can in rare cases be some kind of virus.

Earlier in the year 8 of my 10 cats came down with all we could pinpoint was a virus. It moved through all the cats at different rates, most of them had nausea, vomiting, and some had diarrhea. The most severe cats that couldn't keep food down went to the vet for a cerenia shot and fluids. The rest of my cats recovered with the use of pepcid and slippery elm for nausea and vomiting. I feed mostly raw but not all of the sick cats eat raw, or the same raw, so I was never able to connect it to any specific food. 

As others have said, you can't let your cats go long periods of time without food, and if some of them are still not eating you need to get them to the vet for cerenia shot to help get rid of that nausea. 

This just has me poleaxed.  What on earth could they have gotten into?  Huh...I shall ponder...

They each eat a separate diet. Duncan gets crystals, so he is on prescription food. Marigold can't figure out how to eat wet food, so she gets Instinct dry. Flynn only likes one sort of Fancy feast. Everyone had been happily eating their own food for quite some time, until this hit.  Now they're all back on their regular foods and everyone is eating just fine and even more than fine. There is some cross-over, Marigold likes to lick wet food but can't figure out how to actually eat it. Flynn snitches some of Duncan's prescription diet. Duncan only very rarely eats Flynn's food and I'm cautious about him eating Marigold's (dry food). 

The only possibility is a can of bad Fancy Feast that Marigold licked but Duncan didn't eat much (if any) of. Marigold was at the tail-end of her bag of food and Duncan and Flynn get new cans twice a day.

It remains a mystery!