Re: Burst open abscess on cat
Striveon's suggestions are great ones. If you don't have coconut oil or oil of oregano, GET THEM! Health food store colloidal silver is perhaps OK and you really, really do need the colloidal silver - but it will not likely be anywhere nearly as good as the silver from Utopia Silver.
I don't care how much you paid for the antibiotics, they are not likely to work as well as the silver and other items - though heeding mo123's advice on how to use them would likely be good, at least until you get the other items you need. I personally think that keeping the area lubricated in some manner to allow it to drain as much as needed would be a good idea.
If the antibiotics do not appear to be working, then you REALLY need the silver and other natural items.
You wanted help here and you have now gotten recommendations from a fellow member whose cat had a very similar problem (and they agree with the colloidal silver I recommended) So the solution you sought appears to be at hand.
Best of wishes for your tabby girl.
DQ.