Sickly 1 in a half yr old male tabby

Question
Our cat " LOUIE" was very healthy up until yesterday.He had started  vomiting brown almost reddish vomit and his stools are with alot of mucus.We took him in right away and the vet called this morning ,gave him antibiotics,etc. He is doing a scan today.He said something ate him up.We have checked the house thoroughly,and he is an indoor cat only.What do you think it could be? The vet mentioned abdominal obstructioned.He also said his liver has been affected.He told us he was stable at the moment.What are your thoughts please.

Answer
Usually when an indoor cat has this problem it is plant related or he got into some food wrapped in foil or string.
Brown and reddish vomit is a sign of blood in the small intestine or lower stomach.

The liver is affected due to the buildup of toxins from the bacterial assault or sometimes the actual ingested item.

He could've gotten into some Tylenol from the sound of his symptoms.
I don't know of any cat that would eat it intentionally but cats are all different.House plants are the major intoxicant of cats and string can wreak havoc with their intestines and stomach. After that I would say its swallowing something very small but really that is very rare. The worst case I ever saw was a cat that swallowed a thread with the needle attached. There wasn't any vomiting involved however.

I hope that he finds the problem and that Louie recovers fully. If he is stable that is a good sign for now.
My prayers are with him and you.