Weird growth

We noticed a large nodule in our dogs groin area. It was very red and swollen at first, after a few days of the cone and antimicrobial spray it shrunk some and developed a blackish tip, but as soon as the cone came off he messed with it more. It is definitely smaller than it was but it is hard and we can't figure out what it is. 

Hello - For simplification, there are two types of skin lesion - the ones where the cell structure has changed, as in cancer, benign cancer, hyperplasia (overgrowth) etc, and the ones brought about by the inflammatory response e.g. a reaction to a foreign body, allergy, to the body's own tissue (auto-immune) or to bacteria . yeast / viruses etc.  Where it gets confusing, is that of course cancerous growths can become inflamed and inflammatory growths could have cancer cells in there too.  I'm afraid that I can't see the pictures at time of writing, but I'm not too upset about that,because it's virtually impossible to tell by looking at a lump what sort of cells are in a lump.  As a rough guide, inflammation tends to itch and cancer tends not to, but as I said, mixtures occur so this isn't such a good rule that anyone would rely on it.   Anyway, in the case you describe, it sounds as though things cleared up with some treatment but became worse again.  If your dog didn't scratch or bite the area for long enough, perhaps if superficial products were used (we don't tend to give oral antibiotics for these these days) and something to stop any itching, the area might have chance to clear.  However, this does rely on a robust treatment regeme such that self-trauma is not an option - a collar alone can be helpful but occasionally pain relief and anti-inflammatories, in order that the skin simply doesn't itch, might be the way forward.  Skin is only skin-deep, it is true, but it is also crucial;  lots of the body's nerve-endings are there and whether cancerous or not, it can tend to hurt.  Patient nursing until the area is completely healed is often advised.  Every time it flares up again, the prospect of improving things gets a little harder, so we would strongly recommend veterinary involvement.  They may also decide to biopsy.

PLEASE IGNORE PREVIOUS RESPONSE   i have written this in the incorrect column!   There are several possibilities for this one, including infectious agents , foreign bodies, etc. I cannot identify this and I'm afraid it needs to be shown to your vet - perhaps they would triage (find the appropriate day for you to be seen) from the photograph.

To give some background, the first post is actually completely relevant to most lumps, but didn't consider a group of inflammatory lumps e.g. viral ones or insect bites, or foreign bodies, any of which might become relevant here.  I'm not sure where in the world you are or whether there is anything specific to your area or dog that I might not have considered (eg. a particular sort of parasite); but triage by a local vet from the excellent photo should make sure that your appointment is within a sensible time-frame, just in case.