Like its been said, snakes don't have liquid pus. They have some liquid around the pus sometimes, but the pus is usually a solid mass, much like cottage cheese. It has to be surgically removed. Any injury and swelling around the mouth is particularly painful as well and very prone to a nasty infection.
I lost one of the coolest snake's I've ever had to precisely an infection such as that. And I did take him to the Vet, many times actually, since that was one snake I couldn't give shots to unassisted, he was just to powerful. (BIG Borneo Blood Python) Never ever aggressive, simply tried to get away. Even between the vet and I we had to struggle to hold him still. He too developed the issue after a feeding. He too hit the rat super hard. He had the pus excised twice. But the infection kept spreading despite all we did, despite all the shots. His was on the side of the mouth and it eventually swelled so bad it started to push his eye out. I tried so hard, so did the Vet, but when the poor guy started to cruise his cage back and forth it was time to let him go.
I don't play around with stuff like that.
It means nothing that she still has a feeding response. Its an instinct and she is a retic. If you wait until she won't or can't eat anymore, most likely you will have a septic snake. In your original post you said that "her mouth looked like this for 2 weeks" A simple and uncomplicated swelling would have went down by now. Enlarging the picture you can see a tiny puncture in the middle of the swelling, some reddish but also some whitish discoloration. It looks very painful.