My Bearded Dragon has a horrible infection on her left eye.?

It has only gotten larger over the last week, and it's obviously causing her a great deal of pain. I tried to look under it, using a piece of toilet paper, so I wasn't touching it with my fingers. I had barely touched it, when she jumped nearly out of her skin. Poor baby! I've tried adding veggies with vit A, in case it was a deficiency, but I don't think that's what it is. Can someone help me please? I am very worried! It's black towards the eye, and then the outside of the sore is a giant bubble that looks like it might be full of puss, it's definitely a yellowish color.