Stray Needs Help Bad

Hi everyone /Wave, We are new here & desperate 

I found this upon search http://www.medhelp.org/posts/Cats/human-antibiotics-for-cats/show/418132

We have A Male Stray, He is part of our "Pride" ,He is the Father of All of our Cats (except Momma's, The Adult Female) He has been attacked by IDK? . possibly an Opossum (There is one very near too our house) "Shrek" The male stray, has an open wound on his head @ his ear. Its now Very swollen/infected. Looks like an "Abscess" (Like a tooth ?) But we were given some antibiotic from a friend who is "A Vet" (not sure about that) but He gave us Bactrim,we mixed a very small portion in w/ a full can of cat food & he eat 1 bite an ran off w/ foam coming from his mouth?!?!? 

Is this going to kill him!?!?!?! 

We can afford a visit to a Vet & if we call animal control they will most likely euthanize him. We are trying to adopt him (very slowly gaining trust) what can we do?

We will try the Amoxicillan instead , but will the Bactrim hurt him? 

Is there any thing else we can do to comfort him  ?

And Yes we understand "We" are not Doctors....but no one will help this animal.

We Just can afford to spend money in that manor .

Thanks for your Advise

MeowManMensa

Welcome to the site I am sorry Shrek is injured. Here is a link on Bactrim http://www.1800petmeds.com/Sulfamethoxazole+and+Trimethoprim+Tablets+Double+Strength-prod10046.html might give you some information. I have never used this antibiotic and most vets don't prescribe because it is not FDA approved. Obviously the Bactrim is a bit bitter - but it does say you can mix in food and that is why your vet probably prescribed this one. This is a very tricky situation - trying to medicate a stray cat. If one of my strays/ferals are injured like that I trap them and get them to a vet. I then keep them in a secluded area in my house in a large cat playpen/enclosure to be able to dose the medication properly. If you have many cat's outside, then you cannot be sure this one will get all of the medication. OR if he will even eat the food that is medicated. If he is not taking in the full dose - it will do nothing to help him. I am sorry - it is really tough when the ferals get injured/sick. I know of other's who will have the cat boarded at the vets until they are able to be set free again. Much luck with Shrek and keep us posted

If there is any chance of bringing him to the vet, you may ask whether Convenia (an antibiotic injection) is something that might help in your situation.