To get pus from a wound, it has to be forced out. Chicken pus isn't runny like human pus. It's like candle wax.(Gads, what a topic before breakfast).
Tumors come in two flavors. Malignant and benign. No way to tell which without a biopsy, which you can talk a vet into if you are clever. They...
Here's a tip for making it easier to get the pus out of the wound, if that's what this is. Apply hot compresses, but not too hot that it burns, to the abscess. That will draw the pus to the surface and make it easier to express it.
The penicillin is a good idea. But wound care is absolutely essential in tandem with the antibiotic.
There is a simple way to test whether or not you are dealing with a tumor or an abscess. Squeeze it and see if pus comes out or just blood. If pus comes out, you are dealing with bacterial...