lost cat retrieved, 33 days later, vomits everything he eats

Once he was lost but now he's found. Thanks be to God.

But Oogie can't keep anything down. He puked 3 times today alone. I collected him from "shelter" on Thursday, where they practically drowned him in Frontline and gave a rabies shot (???). He's very interested in eating, cleans himself some, and tries to get out of the house, but is understandably weak. He needs strength, needs to keep some food down in order to derive strength and avoid that scary fatty liver disease.
Been giving him canned friskies, fancy feast, chicken, turkey, baby food. After he puked 45 minutes ago, I gave him a teaspoon of fancy feast and I figured one more serving before bed, hopefully the smaller servings won't overwhelm his stomach.
Tomorrow I'm resolved to give him a warm bath and wash that poison off. I may be able to take him to a vet Tuesday. Any help would be greatly appreciated though.

I forgot to mention - he's practically skin and bones.

I am so glad you found your lost cat. He sounds like he really needs a vet visit. Did the shelter give him any fluids? Vomiting this much is very dehydrating. How long did the shelter have him? Has he been vomiting there as well or just since you got him back?

The pound only had him overnight. He drinks water all the time. I'm not so much worried about dehydration as I am about tossing up his meals.

This is weird.  Have you tried plain boiled chicken?  You could boil some with no seasonings, shred and then mix in some of the broth and offer to him.  I'd call the vet tomorrow and get some advice. He needs to see the vet sooner rather than later.
 

From working at a shelter, being around shelter cats and cats that have been lost and wandering I can offer a couple ideas. It could be some kind of internal parasite picked up from his time wandering, getting used to richer food again, or just stress. Small meals are a good idea and it's great he's drinking. I'm glad you can reach your vet in the morning. You may need a de-wormer or just time and going slow with food or small bland meals for a while. The rabies shot was probably a city ordinance and the flea treatment because fleas are a big problem with the number of animals shelters deal with coming in. The severity of the flea problem in a shelter environment means the chemical treatments are the lesser of two evils.

I'm so glad you got him back though! Your TLC and help from the vet should bring him back to full health soon!
 

My sister had about this same type of thing happen with her cat.  He was gone for about 20 days in the middle of winter.  She figures he got shut in someone's garage.  He had intestinal, vomiting issues when he came home and was very dehydrated.  After several months, he was still throwing up fairly regularly and still had diarrhea.  The vet said he had probably picked up some bad bacteria.  She treated him with clavamox and then probiotics on his food.  It seemed to really help.

Dahlia, I just gave him a little clava something in a spoon. We have it for a small kitten with a leg wound (another head/heartache). After that I gave him mashed boiled chicken and rice w/probably too much salt (can't get mother to listen). I did buy pedialyte, didn't give any yet.
I guess any amoxycylin product will work. You can even buy it for aquarium fish. Question is how much to give.

If you can get me more specifics i'd appreciate it. He is going to a vet first thing tomorrow morning.

I can ask my sister but I really think the vet should prescribe the dosage for the clavamox.  My sister's cat didn't react well to the clava (it upset his stomach even more) so she had to wait until he had put some weight back on to then kill off the bad bacteria and replace it with good bacteria (the probiotics).  Maybe just mention to the vet that you know someone who had a cat in a similar situation and this is what they had to do.  Just keep up with the small meals for now until you can get him to the vet.  Drinking water is very important so it is good your cat is hydrating.

How's he doing and what did the vet say?
 

No throwups after 4 hours now. He walked into the room and seemed wobbly. Stood in one spot.for a few minutes, looked like he was leaning to one side. He layed down. He ate maybe 2 tablespoons or so of chicken rice and broth. A drop/blob of clav- maybe 2/3 the size of a dime. Also gave him a bit of ensure. Hopefully the food in his stomach willstay put and strengthen him

Hit send too soon. I hope his kidneys or liver aren't damaged.

He sees the vet at 8am tomorrow.

He really needs to see the vet, especially after being on his own outside for so long. No telling what kind of parasites and other things he picked up.  After they've gotten out, even if overnight, a check up at the vet's is recommended.
 

5 1/2 hours after I started him on ckick/rice. So far so good. He wants something else it seems, but he begins to eat when I tell him it's good for him. I'll keep you all posted.