Cats in house having strange symptoms

Hello. I have cats in my home that are having strange symptoms. They have brown clumps of stuff by their mouths and all of them when they swallow, it almost looks like they have trouble. All of them are eating okay except for one. She is not really eating and having more brownish drool coming from her mouth

Please call your vet or their emergency cover to have this case triaged right away.  When you've had chance to do that .....  thank you for this interesting question.  Interesting because its relatively unusual for a household of cats ( I don't know whether you have a pair or a whole colony, or their ages or breeds), to come down with the same abnormality at once.  I suppose that there are a few different scenarios in which this might happen: They have been subjected to the same mishap, which caused the same symptoms in each of them.   I wondered about bleeding into the gut (a common result of poisoning), but gut contents tend to be black and not brown in that scenario.  Other vomit could look like this however, which might result from any number of illnesses or toxins.  Dental disease would cause discoloured hypersalivation but tends not to pass between cats; they would be unlucky to eg all swallow fishhooks at once.  Perhaps there are things that they could all have eaten that would cause a foul vomit or hypersalivation answering this description, or toxins they might have licked together.  Perhaps they are related, all prone to pancreatitis and found a fatty meal together.  Perhaps they shared prey that was going off.  From the little that I know, there is potentially a long list of possible scenarios.  Your vet will hold a similar mental list  and be able to ask ypu questions  and make judgements, narrowing the possibities down to a manageable number.  Because drooling is so often linked to feeling very ill and nauseous, and because you mention trouble swallowing, your cats might be at risk of dehydration, kidney disease or worsening breathing problems and the emergency vet may well want to see them.   There are some infectious diseases that may look like this also.   I hope that they are able to give you some help.